Fix Maven build for metrics-graphite
Add YarnClientClusterScheduler and Backend.

With this scheduler, the user application is launched locally,
While the executor will be launched by YARN on remote nodes.

This enables spark-shell to run upon YARN.
Consolidated both mapPartitions related RDDs into a single MapPartitionsRDD.
Also changed the semantics of the index parameter in mapPartitionsWithIndex from the partition index of the output partition to the partition index in the current RDD.
Update tuning.md

Clarify when serializer is used based on recent user@ mailing list discussion.
Added unit tests for size estimation for specialized hash sets and maps.
Incorporated ideas from pull request #200.
- Use Murmur Hash 3 finalization step to scramble the bits of HashCode
  instead of the simpler version in java.util.HashMap; the latter one
  had trouble with ranges of consecutive integers. Murmur Hash 3 is used
  by fastutil.

- Don't check keys for equality when re-inserting due to growing the
  table; the keys will already be unique

- Remember the grow threshold instead of recomputing it on each insert
Initial commit of adding histogram functionality to the DoubleRDDFunctions.
Add tests for the Java implementation.
CR feedback
Remove extranious type definitions from inside of tests
Remove extranious type declerations
Remove explicit boxing
Add spaces
Fix the test
Improve docs for shuffle instrumentation
Simplified syntax to check if job and stage exist