Spark-915 segregate scripts

Yarn refactor

fix spark on yarn after the sparkConf changes

This fixes it so that spark on yarn now compiles and works after the sparkConf changes.

There are also other issues I discovered along the way that are broken:
- mvn builds for yarn don't assemble correctly
- unset SPARK_EXAMPLES_JAR isn't handled properly anymore
- I'm pretty sure spark.conf doesn't actually work as its not distributed with yarn

those things can be fixed in separate pr unless others disagree.

Remove erroneous FAILED state for killed tasks.

Currently, when tasks are killed, the Executor first sends a
status update for the task with a "KILLED" state, and then
sends a second status update with a "FAILED" state saying that
the task failed due to an exception. The second FAILED state is
misleading/unncessary, and occurs due to a NonLocalReturnControl
Exception that gets thrown due to the way we kill tasks. This
commit eliminates that problem.

I'm not at all sure that this is the best way to fix this problem,
so alternate suggestions welcome. @rxin guessing you're the right
person to look at this.

Improvements to DStream window ops and refactoring of Spark's CheckpointSuite

- Added a new RDD - PartitionerAwareUnionRDD. Using this RDD, one can take multiple RDDs partitioned by the same partitioner and unify them into a single RDD while preserving the partitioner. So m RDDs with p partitions each will be unified to a single RDD with p partitions and the same partitioner. The preferred location for each partition of the unified RDD will be the most common preferred location of the corresponding partitions of the parent RDDs. For example, location of partition 0 of the unified RDD will be where most of partition 0 of the parent RDDs are located.
- Improved the performance of DStream's reduceByKeyAndWindow and groupByKeyAndWindow. Both these operations work by doing per-batch reduceByKey/groupByKey and then using PartitionerAwareUnionRDD to union the RDDs across the window. This eliminates a shuffle related to the window operation, which can reduce batch processing time by 30-40% for simple workloads.
- Fixed bugs and simplified Spark's CheckpointSuite. Some of the tests were incorrect and unreliable. Added missing tests for ZippedRDD. I can go into greater detail if necessary.
- Added mapSideCombine option to combineByKeyAndWindow.

Removed redundant TaskSetManager.error() function.

This function was leftover from a while ago, and now just
passes all calls through to the abort() function, so this
commit deletes it.

SPARK-991: Report information gleaned from a Python stacktrace in the UI

Scala:

- Added setCallSite/clearCallSite to SparkContext and JavaSparkContext.
  These functions mutate a LocalProperty called "externalCallSite."
- Add a wrapper, getCallSite, that checks for an externalCallSite and, if
  none is found, calls the usual Utils.formatSparkCallSite.
- Change everything that calls Utils.formatSparkCallSite to call
  getCallSite instead. Except getCallSite.
- Add wrappers to setCallSite/clearCallSite wrappers to JavaSparkContext.

Python:

- Add a gruesome hack to rdd.py that inspects the traceback and guesses
  what you want to see in the UI.
- Add a RAII wrapper around said gruesome hack that calls
  setCallSite/clearCallSite as appropriate.
- Wire said RAII wrapper up around three calls into the Scala code.
  I'm not sure that I hit all the spots with the RAII wrapper. I'm also
  not sure that my gruesome hack does exactly what we want.

One could also approach this change by refactoring
runJob/submitJob/runApproximateJob to take a call site, then threading
that parameter through everything that needs to know it.

One might object to the pointless-looking wrappers in JavaSparkContext.
Unfortunately, I can't directly access the SparkContext from
Python---or, if I can, I don't know how---so I need to wrap everything
that matters in JavaSparkContext.

Conflicts:
	core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala

Currently, when tasks are killed, the Executor first sends a
status update for the task with a "KILLED" state, and then
sends a second status update with a "FAILED" state saying that
the task failed due to an exception. The second FAILED state is
misleading/unncessary, and occurs due to a NonLocalReturnControl
Exception that gets thrown due to the way we kill tasks. This
commit eliminates that problem.

This function was leftover from a while ago, and now just
passes all calls through to the abort() function, so this
commit deletes it.

Merge branch 'scripts-reorg' of github.com:shane-huang/incubator-spark into spark-915-segregate-scripts

Conflicts:
	bin/spark-shell
	core/pom.xml
	core/src/main/scala/org/apache/spark/SparkContext.scala
	core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/CoarseMesosSchedulerBackend.scala
	core/src/main/scala/org/apache/spark/ui/UIWorkloadGenerator.scala
	core/src/test/scala/org/apache/spark/DriverSuite.scala
	python/run-tests
	sbin/compute-classpath.sh
	sbin/spark-class
	sbin/stop-slaves.sh