Spark initi the properties CoarseGrainedSchedulerBackend.start
```scala
    // TODO (prashant) send conf instead of properties
    driverEndpoint = rpcEnv.setupEndpoint(
      CoarseGrainedSchedulerBackend.ENDPOINT_NAME, new DriverEndpoint(rpcEnv, properties))
```
Then the yarn logic will set some configuration but not update in this `properties`.
So `Executor` won't gain the `properties`.

[Jira](https://issues.apache.org/jira/browse/SPARK-8687)

Author: huangzhaowei <carlmartinmax@gmail.com>

Closes #7066 from SaintBacchus/SPARK-8687 and squashes the following commits:

1de4f48 [huangzhaowei] Ensure all necessary properties have already been set before startup ExecutorLaucher

I've updated default values in comments, documentation, and in the command line builder to be 1g based on comments in the JIRA. I've also updated most usages to point at a single variable defined in the Utils.scala and JavaUtils.java files. This wasn't possible in all cases (R, shell scripts etc.) but usage in most code is now pointing at the same place.

Please let me know if I've missed anything.

Will the spark-shell use the value within the command line builder during instantiation?

Author: Ilya Ganelin <ilya.ganelin@capitalone.com>

Closes #7132 from ilganeli/SPARK-3071 and squashes the following commits:

4074164 [Ilya Ganelin] String fix
271610b [Ilya Ganelin] Merge branch 'SPARK-3071' of github.com:ilganeli/spark into SPARK-3071
273b6e9 [Ilya Ganelin] Test fix
fd67721 [Ilya Ganelin] Update JavaUtils.java
26cc177 [Ilya Ganelin] test fix
e5db35d [Ilya Ganelin] Fixed test failure
39732a1 [Ilya Ganelin] merge fix
a6f7deb [Ilya Ganelin] Created default value for DRIVER MEM in Utils that's now used in almost all locations instead of setting manually in each
09ad698 [Ilya Ganelin] Update SubmitRestProtocolSuite.scala
19b6f25 [Ilya Ganelin] Missed one doc update
2698a3d [Ilya Ganelin] Updated default value for driver memory

This commit allows `dev/merge_spark_pr.py` to use personal GitHub OAuth tokens in order to make authenticated requests. This is necessary to work around per-IP rate limiting issues.

To use a token, just set the `GITHUB_OAUTH_KEY` environment variable.  You can create a personal token at https://github.com/settings/tokens; we only require `public_repo` scope.

If the script fails due to a rate-limit issue, it now logs a useful message directing the user to the OAuth token instructions.

Author: Josh Rosen <joshrosen@databricks.com>

Closes #7136 from JoshRosen/pr-merge-script-oauth-authentication and squashes the following commits:

4d011bd [Josh Rosen] Fix error message
23d92ff [Josh Rosen] Support GitHub OAuth tokens in dev/merge_spark_pr.py

Author: Holden Karau <holden@pigscanfly.ca>

Closes #7171 from holdenk/SPARK-8769-toLocalIterator-documentation-improvement and squashes the following commits:

97ddd99 [Holden Karau] Add note

Author: Holden Karau <holden@pigscanfly.ca>

Closes #7172 from holdenk/SPARK-8771-actor-system-deprecation-tag-uses-deprecated-deprecation-tag and squashes the following commits:

7f1455b [Holden Karau] Add .0s to the versions for the derpecated anotations in SparkEnv.scala
ca13c9d [Holden Karau] Add a version to the deprecated annotation for the actorSystem in SparkEnv

If `fs.hdfs.impl.disable.cache` was `false`(default), `FileSystem` will use the cached `DFSClient` which use old token.
[AMDelegationTokenRenewer](https://github.com/apache/spark/blob/master/yarn/src/main/scala/org/apache/spark/deploy/yarn/AMDelegationTokenRenewer.scala#L196)
```scala
    val credentials = UserGroupInformation.getCurrentUser.getCredentials
    credentials.writeTokenStorageFile(tempTokenPath, discachedConfiguration)
```
Although the `credentials` had the new Token, but it still use the cached client and old token.
So It's better to set the `fs.hdfs.impl.disable.cache`  as `true` to avoid token expired.

[Jira](https://issues.apache.org/jira/browse/SPARK-8688)

Author: huangzhaowei <carlmartinmax@gmail.com>

Closes #7069 from SaintBacchus/SPARK-8688 and squashes the following commits:

f94cd0b [huangzhaowei] modify function parameter
8fb9eb9 [huangzhaowei] explicit  the comment
0cd55c9 [huangzhaowei] Rename function name to be an accurate one
cf776a1 [huangzhaowei] [SPARK-8688][YARN]Bug fix: disable the cache fs to gain the HDFS connection.

In YarnClientSchedulerBackend.stop(), added a check for monitorThread.

Author: Devaraj K <devaraj@apache.org>

Closes #7153 from devaraj-kavali/master and squashes the following commits:

66be9ad [Devaraj K] https://issues.apache.org/jira/browse/SPARK-8754 YarnClientSchedulerBackend doesn't stop gracefully in failure conditions

cc chenghao-intel  adrian-wang

Author: zhichao.li <zhichao.li@intel.com>

Closes #7113 from zhichao-li/unhex and squashes the following commits:

379356e [zhichao.li] remove exception checking
a4ae6dc [zhichao.li] add udf_unhex to whitelist
fe5c14a [zhichao.li] add todigit
607d7a3 [zhichao.li] use checkInputTypes
bffd37f [zhichao.li] change to use Hex in apache common package
cde73f5 [zhichao.li] update to use AutoCastInputTypes
11945c7 [zhichao.li] style
c852d46 [zhichao.li] Add function unhex

[SPARK-8660] [MLLIB] removed > symbols from comments in LogisticRegressionSuite.scala for ease of copypaste

'>' symbols removed from comments in LogisticRegressionSuite.scala, for ease of copypaste

also single-lined the multiline commands (is this desirable, or does it violate style?)

Author: Rosstin <asterazul@gmail.com>

Closes #7167 from Rosstin/SPARK-8660-2 and squashes the following commits:

f4b9bc8 [Rosstin] SPARK-8660 restored character limit on multiline comments in LogisticRegressionSuite.scala
fe6b112 [Rosstin] SPARK-8660 > symbols removed from LogisticRegressionSuite.scala for easy of copypaste
39ddd50 [Rosstin] Merge branch 'master' of github.com:apache/spark into SPARK-8661
5a05dee [Rosstin] SPARK-8661 for LinearRegressionSuite.scala, changed javadoc-style comments to regular multiline comments to make it easier to copy-paste the R code.
bb9a4b1 [Rosstin] Merge branch 'master' of github.com:apache/spark into SPARK-8660
242aedd [Rosstin] SPARK-8660, changed comment style from JavaDoc style to normal multiline comment in order to make copypaste into R easier, in file classification/LogisticRegressionSuite.scala
2cd2985 [Rosstin] Merge branch 'master' of github.com:apache/spark into SPARK-8639
21ac1e5 [Rosstin] Merge branch 'master' of github.com:apache/spark into SPARK-8639
6c18058 [Rosstin] fixed minor typos in docs/README.md and docs/api.md

Our current BinaryExpression abstract class is not for generic binary expressions, i.e. it requires left/right children to have the same type. However, due to its name, contributors build new binary expressions that don't have that assumption (e.g. Sha) and still extend BinaryExpression.

This patch creates a new BinaryOperator abstract class, and update the analyzer o only apply type casting rule there. This patch also adds the notion of "prettyName" to expressions, which defines the user-facing name for the expression.

Author: Reynold Xin <rxin@databricks.com>

Closes #7174 from rxin/binary-opterator and squashes the following commits:

f31900d [Reynold Xin] [SPARK-8770][SQL] Create BinaryOperator abstract class.
fceb216 [Reynold Xin] Merge branch 'master' of github.com:apache/spark into binary-opterator
d8518cf [Reynold Xin] Updated Python tests.

This reverts commit 27277899.

Our current BinaryExpression abstract class is not for generic binary expressions, i.e. it requires left/right children to have the same type. However, due to its name, contributors build new binary expressions that don't have that assumption (e.g. Sha) and still extend BinaryExpression.

This patch creates a new BinaryOperator abstract class, and update the analyzer o only apply type casting rule there. This patch also adds the notion of "prettyName" to expressions, which defines the user-facing name for the expression.

Author: Reynold Xin <rxin@databricks.com>

Closes #7170 from rxin/binaryoperator and squashes the following commits:

51264a5 [Reynold Xin] [SPARK-8770][SQL] Create BinaryOperator abstract class.

Use UTF-8 to encode the name of column in Python 2, or it may failed to encode with default encoding ('ascii').

This PR also fix a bug when there is Java exception without error message.

Author: Davies Liu <davies@databricks.com>

Closes #7165 from davies/non_ascii and squashes the following commits:

02cb61a [Davies Liu] fix tests
3b09d31 [Davies Liu] add encoding in header
867754a [Davies Liu] support non-ascii character in column names

Otherwise other tests don't log anything useful...

Author: Marcelo Vanzin <vanzin@cloudera.com>

Closes #7140 from vanzin/SPARK-3444 and squashes the following commits:

de14836 [Marcelo Vanzin] Better fix.
6cff13a [Marcelo Vanzin] [SPARK-3444] [core] Restore INFO level after log4j test.

copy() of generated Row doesn't check nullability of columns

Author: Davies Liu <davies@databricks.com>

Closes #7163 from davies/fix_copy and squashes the following commits:

661a206 [Davies Liu] fix copy of generated row

Author: jerryshao <saisai.shao@intel.com>

Closes #7120 from jerryshao/SPARK-7820 and squashes the following commits:

6902439 [jerryshao] fix Java8-tests suite compile error under sbt

Author: zsxwing <zsxwing@gmail.com>

Closes #6830 from zsxwing/flume-python and squashes the following commits:

78dfdac [zsxwing] Fix the compile error in the test code
f1bf3c0 [zsxwing] Address TD's comments
0449723 [zsxwing] Add sbt goal streaming-flume-assembly/assembly
e93736b [zsxwing] Fix the test case for determine_modules_to_test
9d5821e [zsxwing] Fix pyspark_core dependencies
f9ee681 [zsxwing] Merge branch 'master' into flume-python
7a55837 [zsxwing] Add streaming_flume_assembly to run-tests.py
b96b0de [zsxwing] Merge branch 'master' into flume-python
ce85e83 [zsxwing] Fix incompatible issues for Python 3
01cbb3d [zsxwing] Add import sys
152364c [zsxwing] Fix the issue that StringIO doesn't work in Python 3
14ba0ff [zsxwing] Add flume-assembly for sbt building
b8d5551 [zsxwing] Merge branch 'master' into flume-python
4762c34 [zsxwing] Fix the doc
0336579 [zsxwing] Refactor Flume unit tests and also add tests for Python API
9f33873 [zsxwing] Add the Python API for Flume

See failure: [https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/36133/console]

CC yanboliang  mengxr

Author: Joseph K. Bradley <joseph@databricks.com>

Closes #7164 from jkbradley/pic-python-test and squashes the following commits:

156d55b [Joseph K. Bradley] removed flaky python PIC test

jira: https://issues.apache.org/jira/browse/SPARK-8308

1. add some missing save/load in python examples. , LogisticRegression, LinearRegression and NaiveBayes
2. tune down iterations for MatrixFactorization, since current number will trigger StackOverflow for default java configuration (>1M)

Author: Yuhao Yang <hhbyyh@gmail.com>

Closes #6760 from hhbyyh/docUpdate and squashes the following commits:

9bd3383 [Yuhao Yang] update scala example
8a44692 [Yuhao Yang] Merge remote-tracking branch 'upstream/master' into docUpdate
077cbb8 [Yuhao Yang] Merge remote-tracking branch 'upstream/master' into docUpdate
3e948dc [Yuhao Yang] add missing save load for python example

Implement missing API in pyspark.

MLUtils
* appendBias
* loadVectors

`kFold` is also missing however I am not sure `ClassTag` can be passed or restored through python.

Author: lewuathe <lewuathe@me.com>

Closes #5707 from Lewuathe/SPARK-6263 and squashes the following commits:

16863ea [lewuathe] Merge master
3fc27e7 [lewuathe] Merge branch 'master' into SPARK-6263
6084e9c [lewuathe] Resolv conflict
d2aa2a0 [lewuathe] Resolv conflict
9c329d8 [lewuathe] Fix efficiency
3a12a2d [lewuathe] Merge branch 'master' into SPARK-6263
1d4714b [lewuathe] Fix style
b29e2bc [lewuathe] Remove scipy dependencies
e32eb40 [lewuathe] Merge branch 'master' into SPARK-6263
25d3c9d [lewuathe] Remove unnecessary imports
7ec04db [lewuathe] Resolv conflict
1502d13 [lewuathe] Resolv conflict
d6bd416 [lewuathe] Check existence of scipy.sparse
5d555b1 [lewuathe] Construct scipy.sparse matrix
c345a44 [lewuathe] Merge branch 'master' into SPARK-6263
b8b5ef7 [lewuathe] Fix unnecessary sort method
d254be7 [lewuathe] Merge branch 'master' into SPARK-6263
62a9c7e [lewuathe] Fix appendBias return type
454c73d [lewuathe] Merge branch 'master' into SPARK-6263
a353354 [lewuathe] Remove unnecessary appendBias implementation
44295c2 [lewuathe] Merge branch 'master' into SPARK-6263
64f72ad [lewuathe] Merge branch 'master' into SPARK-6263
c728046 [lewuathe] Fix style
2980569 [lewuathe] [SPARK-6263] Python MLlib API missing items: Utils

improve the empty check in `parseAttributeName` so that we can allow empty string as column name.
Close https://github.com/apache/spark/pull/7117

Author: Wenchen Fan <cloud0fan@outlook.com>

Closes #7149 from cloud-fan/8621 and squashes the following commits:

efa9e3e [Wenchen Fan] support empty string

This patch doesn't actually introduce any code that uses the new ExpectsInputTypes. It just adds the trait so others can use it. Also renamed the old expectsInputTypes function to just inputTypes.

We should add implicit type casting also in the future.

Author: Reynold Xin <rxin@databricks.com>

Closes #7151 from rxin/expects-input-types and squashes the following commits:

16cf07b [Reynold Xin] [SPARK-8752][SQL] Add ExpectsInputTypes trait for defining expected input types.

1. Update the pattern 'expect_true(a == b)' to 'expect_equal(a, b)'.
2. Update the pattern 'expect_true(inherits(a, b))' to 'expect_is(a, b)'.
3. Update the pattern 'expect_true(identical(a, b))' to 'expect_identical(a, b)'.

Author: Sun Rui <rui.sun@intel.com>

Closes #7152 from sun-rui/SPARK-7714 and squashes the following commits:

8ad2440 [Sun Rui] Fix test case errors.
8fe9f0c [Sun Rui] Update the pattern 'expect_true(identical(a, b))' to 'expect_identical(a, b)'.
f1b8005 [Sun Rui] Update the pattern 'expect_true(inherits(a, b))' to 'expect_is(a, b)'.
f631e94 [Sun Rui] Update the pattern 'expect_true(a == b)' to 'expect_equal(a, b)'.

[SPARK-8763] [PYSPARK] executing run-tests.py with Python 2.6 fails with absence of subprocess.check_output function

Running run-tests.py with Python 2.6 cause following error:

```
Running PySpark tests. Output is in python//Users/tomohiko/.jenkins/jobs/pyspark_test/workspace/python/unit-tests.log
Will test against the following Python executables: ['python2.6', 'python3.4', 'pypy']
Will test the following Python modules: ['pyspark-core', 'pyspark-ml', 'pyspark-mllib', 'pyspark-sql', 'pyspark-streaming']
Traceback (most recent call last):
  File "./python/run-tests.py", line 196, in <module>
    main()
  File "./python/run-tests.py", line 159, in main
    python_implementation = subprocess.check_output(
AttributeError: 'module' object has no attribute 'check_output'
...
```

The cause of this error is using subprocess.check_output function, which exists since Python 2.7.
(ref. https://docs.python.org/2.7/library/subprocess.html#subprocess.check_output)

Author: cocoatomo <cocoatomo77@gmail.com>

Closes #7161 from cocoatomo/issues/8763-test-fails-py26 and squashes the following commits:

cf4f901 [cocoatomo] [SPARK-8763] backport process.check_output function from Python 2.7

Author: Reynold Xin <rxin@databricks.com>

Closes #7148 from rxin/calludf-closure and squashes the following commits:

00df372 [Reynold Xin] Fixed index out of bound exception.
4beba76 [Reynold Xin] [SPARK-8750][SQL] Remove the closure in functions.callUdf.

Developers have already familiar with `queryExecution.toRDD` as internal row RDD, and we should not add new concept.

Author: Wenchen Fan <cloud0fan@outlook.com>

Closes #7116 from cloud-fan/internal-rdd and squashes the following commits:

24756ca [Wenchen Fan] remove internalRowRDD

Moved all the rules into the companion object.

Author: Reynold Xin <rxin@databricks.com>

Closes #7147 from rxin/SPARK-8749 and squashes the following commits:

c1c6dc0 [Reynold Xin] [SPARK-8749][SQL] Remove HiveTypeCoercion trait.

This patch moved resolve function in Cast case class into the companion object, and renamed it canCast. We can then use this in the analyzer without a Cast expr.

Author: Reynold Xin <rxin@databricks.com>

Closes #7145 from rxin/cast and squashes the following commits:

cd086a9 [Reynold Xin] Whitespace changes.
4d2d989 [Reynold Xin] [SPARK-8748][SQL] Move castability test out from Cast case class into Cast object.

A follow-up pr to address https://github.com/apache/spark/pull/5392#discussion_r33627528

Author: zsxwing <zsxwing@gmail.com>

Closes #7141 from zsxwing/pr5392-follow-up and squashes the following commits:

fcf7b50 [zsxwing] Remove unnecessary synchronized

[SPARK-8535] [PYSPARK] PySpark : Can't create DataFrame from Pandas dataframe with no explicit column name

Because implicit name of `pandas.columns` are Int, but `StructField` json expect `String`.
So I think `pandas.columns` are should be convert to `String`.

### issue

* [SPARK-8535 PySpark : Can't create DataFrame from Pandas dataframe with no explicit column name](https://issues.apache.org/jira/browse/SPARK-8535)

Author: x1- <viva008@gmail.com>

Closes #7124 from x1-/SPARK-8535 and squashes the following commits:

d68fd38 [x1-] modify unit-test using pandas.
ea1897d [x1-] For implicit name of pandas.columns are Int, so should be convert to String.

Rename DiscreteCosineTransformer and related classes to DCT.

Author: Feynman Liang <fliang@databricks.com>

Closes #7138 from feynmanliang/dct-features and squashes the following commits:

e547b3e [Feynman Liang] Fix renaming bug
9d5c9e4 [Feynman Liang] Lowercase JavaDCTSuite variable
f9a8958 [Feynman Liang] Remove old files
f8fe794 [Feynman Liang] Merge branch 'master' into dct-features
894d0b2 [Feynman Liang] Rename DiscreteCosineTransformer to DCT
433dbc7 [Feynman Liang] Test refactoring
91e9636 [Feynman Liang] Style guide and test helper refactor
b5ac19c [Feynman Liang] Use Vector types, add Java test
530983a [Feynman Liang] Tests for other numeric datatypes
195d7aa [Feynman Liang] Implement support for arbitrary numeric types
95d4939 [Feynman Liang] Working DCT for 1D Doubles

This PR updates the rest Actors in core to RpcEndpoint.

Because there is no `ActorSelection` in RpcEnv, I changes the logic of `registerWithMaster` in Worker and AppClient to avoid blocking the message loop. These changes need to be reviewed carefully.

Author: zsxwing <zsxwing@gmail.com>

Closes #5392 from zsxwing/rpc-rewrite-part3 and squashes the following commits:

2de7bed [zsxwing] Merge branch 'master' into rpc-rewrite-part3
f12d943 [zsxwing] Address comments
9137b82 [zsxwing] Fix the code style
e734c71 [zsxwing] Merge branch 'master' into rpc-rewrite-part3
2d24fb5 [zsxwing] Fix the code style
5a82374 [zsxwing] Merge branch 'master' into rpc-rewrite-part3
fa47110 [zsxwing] Merge branch 'master' into rpc-rewrite-part3
72304f0 [zsxwing] Update the error strategy for AkkaRpcEnv
e56cb16 [zsxwing] Always send failure back to the sender
a7b86e6 [zsxwing] Use JFuture for java.util.concurrent.Future
aa34b9b [zsxwing] Fix the code style
bd541e7 [zsxwing] Merge branch 'master' into rpc-rewrite-part3
25a84d8 [zsxwing] Use ThreadUtils
060ff31 [zsxwing] Merge branch 'master' into rpc-rewrite-part3
dbfc916 [zsxwing] Improve the docs and comments
837927e [zsxwing] Merge branch 'master' into rpc-rewrite-part3
5c27f97 [zsxwing] Merge branch 'master' into rpc-rewrite-part3
fadbb9e [zsxwing] Fix the code style
6637e3c [zsxwing] Merge remote-tracking branch 'origin/master' into rpc-rewrite-part3
7fdee0e [zsxwing] Fix the return type to ExecutorService and ScheduledExecutorService
e8ad0a5 [zsxwing] Fix the code style
6b2a104 [zsxwing] Log error and use SparkExitCode.UNCAUGHT_EXCEPTION exit code
fbf3194 [zsxwing] Add Utils.newDaemonSingleThreadExecutor and newDaemonSingleThreadScheduledExecutor
b776817 [zsxwing] Update Master, Worker, Client, AppClient and related classes to use RpcEndpoint

Jira: https://issues.apache.org/jira/browse/SPARK-8727

Author: Tarek Auel <tarek.auel@gmail.com>
Author: Tarek Auel <tarek.auel@googlemail.com>

Closes #7114 from tarekauel/missing-python and squashes the following commits:

ef4c61b [Tarek Auel] [SPARK-8727] revert dataframe change
4029d4d [Tarek Auel] removed dataframe pi and e unit test
66f0d2b [Tarek Auel] removed pi and e from python api and dataframe api; added _to_java_column(col) for strlen
4d07318 [Tarek Auel] fixed python unit test
45f2bee [Tarek Auel] fixed result of pi and e
c39f47b [Tarek Auel] add python api
bd50a3a [Tarek Auel] add missing python functions

Author: Reynold Xin <rxin@databricks.com>

Closes #7137 from rxin/SPARK-8741 and squashes the following commits:

32c7e75 [Reynold Xin] [SPARK-8741][SQL] Remove e and pi from DataFrame functions.

Author: sethah <seth.hendrickson16@gmail.com>

Closes #7029 from sethah/working_on_SPARK-7739 and squashes the following commits:

ef96916 [sethah] Fixing some style issues
efea1f8 [sethah] adding clarification to ChiSqSelector example

Capture the AnalysisException in SQL, hide the long java stack trace, only show the error message.

cc rxin

Author: Davies Liu <davies@databricks.com>

Closes #7135 from davies/ananylis and squashes the following commits:

dad7ae7 [Davies Liu] add comment
ec0c0e8 [Davies Liu] Update utils.py
cdd7edd [Davies Liu] add doc
7b044c2 [Davies Liu] fix python 3
f84d3bd [Davies Liu] capture SQL AnalysisException in Python API

This issue was reported by saurfang. Thanks!

There is a following code in StagePage.scala.

```
                   |width="$serializationTimeProportion%"></rect>
                 |<rect class="getting-result-time-proportion"
                   |x="$gettingResultTimeProportionPos%" y="0px" height="26px"
                   |width="$gettingResultTimeProportion%"></rect></svg>',
               |'start': new Date($launchTime),
               |'end': new Date($finishTime)
             |}
           |""".stripMargin.replaceAll("\n", " ")
```

The last `replaceAll("\n", "")` doesn't work when we checkout and build source code on Windows and deploy on Linux.
It's because when we checkout the source code on Windows, new-line-code is replaced with `"\r\n"` and `replaceAll("\n", "")` replaces only `"\n"`.

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #7133 from sarutak/SPARK-8739 and squashes the following commits:

17fb044 [Kousuke Saruta] Fixed a new-line-code issue

I'm sorry that I made https://github.com/apache/spark/pull/6949 closed by mistake.
I pushed codes again.

And, I added a test code.

>
There is a bug that `U.numCols() = self.nCols` in `IndexedRowMatrix.computeSVD()`
It should have been `U.numCols() = k = svd.U.numCols()`

>
```
self = U * sigma * V.transpose
(m x n) = (m x n) * (k x k) * (k x n) //ASIS
-->
(m x n) = (m x k) * (k x k) * (k x n) //TOBE
```

Author: lee19 <lee19@live.co.kr>

Closes #6953 from lee19/MLlibBugfix and squashes the following commits:

c1812a0 [lee19] [SPARK-8563] [MLlib] Used nRows instead of numRows() to reduce a burden.
4b9803b [lee19] [SPARK-8563] [MLlib] Fixed a build error.
c2ccd89 [lee19] Added a unit test that validates matrix sizes of svd for [SPARK-8563][MLlib]
8373424 [lee19] [SPARK-8563][MLlib] Fixed a bug so that IndexedRowMatrix.computeSVD().U.numCols = k

Because `System.currentTimeMillis()` is not accurate for tasks that only need several milliseconds, sometimes `totalExecutionTime` in `makeTimeline` will be 0. If `totalExecutionTime` is 0, there will the following error in the console.

![screen shot 2015-06-29 at 7 08 55 pm](https://cloud.githubusercontent.com/assets/1000778/8406776/5cd38e04-1e92-11e5-89f2-0c5134fe4b6b.png)

This PR fixes it by using an empty svg tag when `totalExecutionTime` is 0. This is a screenshot for a task that its totalExecutionTime is 0 after fixing it.

![screen shot 2015-06-30 at 12 26 52 am](https://cloud.githubusercontent.com/assets/1000778/8412896/7b33b4be-1ebf-11e5-9100-d6d656af3747.png)

Author: zsxwing <zsxwing@gmail.com>

Closes #7088 from zsxwing/SPARK-8705 and squashes the following commits:

9ee4ef5 [zsxwing] Address comments
ef2ecfa [zsxwing] Don't display rects when totalExecutionTime is 0

Changed GBTRegressor so it does NOT threshold the prediction.  Added test which fails with bug but works after fix.

CC: feynmanliang  mengxr

Author: Joseph K. Bradley <joseph@databricks.com>

Closes #7134 from jkbradley/gbrt-fix and squashes the following commits:

613b90e [Joseph K. Bradley] Changed GBTRegressor so it does NOT threshold the prediction