Support for Apache Spark

This patch adds basic support for launching a
Spark application on YARN in standalone mode.

- support for env specific config through client.cfg
- simple status tracking / error handling
- kills the yarn app on ctrl+c

Change-Id: Ia1b488eef74c2bade31c9c3fc38b8e508d6cee64
Move spark support to contrib

Change-Id: Idf9267c3467bf8c704ab94bc76066762c94dc35f
Add Spark example code

Change-Id: Iea8110bbe0a7bb77c89c733579290c45e386b982
Fix type

Change-Id: I8dfbdf0ab2b6f0a07a13ae169eba8d14553a4920
Merge pull request #274 from edwardnewett/master

Support for Apache Spark