Fixes [SPARK-5434](https://issues.apache.org/jira/browse/SPARK-5434).

Simple demonstration of the problem and the fix:

```
$ spacey_path="/path/with some/spaces"
$ dirname $spacey_path
usage: dirname path
$ echo $?
1
$ dirname "$spacey_path"
/path/with some
$ echo $?
0
```

Author: Nicholas Chammas <nicholas.chammas@gmail.com>

Closes #4224 from nchammas/patch-1 and squashes the following commits:

960711a [Nicholas Chammas] [EC2] Preserve spaces in EC2 path

This patch upgrades `spark-ec2`'s Boto version to 2.34.0, since this is blocking several features.  Newer versions of Boto don't work properly when they're loaded from a zipfile since they try to read a JSON file from a path relative to the Boto library sources.

Therefore, this patch also changes spark-ec2 to automatically download Boto from PyPi if it's not present in `SPARK_EC2_DIR/lib`, similar to what we do in the `sbt/sbt` script. This shouldn't ben an issue for users since they already need to have an internet connection to launch an EC2 cluster.  By performing the downloading in spark_ec2.py instead of the Bash script, this should also work for Windows users.

I've tested this with Python 2.6, too.

Author: Josh Rosen <joshrosen@databricks.com>

Closes #3737 from JoshRosen/update-boto and squashes the following commits:

0aa43cc [Josh Rosen] Remove unused setup_standalone_cluster() method.
f02935d [Josh Rosen] Enable Python deprecation warnings and fix one Boto warning:
587ae89 [Josh Rosen] [SPARK-4890] Upgrade Boto to 2.34.0; automatically download Boto from PyPi instead of packaging it

This issue was uncovered after [this discussion](https://issues.apache.org/jira/browse/SPARK-3398?focusedCommentId=14187471&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14187471).

Don't change the working directory on the user. This breaks relative paths the user may pass in, e.g., for the SSH identity file.

```
./ec2/spark-ec2 -i ../my.pem
```

This patch will preserve the user's current working directory and allow calls like the one above to work.

Author: Nicholas Chammas <nicholas.chammas@gmail.com>

Closes #2988 from nchammas/spark-ec2-cwd and squashes the following commits:

f3850b5 [Nicholas Chammas] pep8 fix
fbc20c7 [Nicholas Chammas] revert to old commenting style
752f958 [Nicholas Chammas] specify deploy.generic path absolutely
bcdf6a5 [Nicholas Chammas] fix typo
77871a2 [Nicholas Chammas] add clarifying comment
ce071fc [Nicholas Chammas] don't change working dir

To preserve quoted command line args (in case options have space in them).

Author: Ori Kremer <ori.kremer@gmail.com>

Closes #1169 from orikremer/quote_cmd_line_args and squashes the following commits:

67e2aa1 [Ori Kremer] quote command line args

for new users to get up and running on EC2.