Add private, minor formatting.
Add RDD.coalesce.
Remove unneeded zipWithIndex.

Also rename r->rdd and remove unneeded extra type info.
Clean up RDDs, mainly to use getSplits.

Also made sure clearDependencies() was calling super, to ensure
the getSplits/getDependencies vars in the RDD base class get
cleaned up.
Change docs on 'reduce' since the merging of local reduces no longer preserves
ordering, so the reduce function must also be commutative.
Adding IPYTHON environment variable support for launching pyspark using ipython shell
Merge pull request #454 from MLnick/ipython

SPARK-685 Adding IPYTHON environment variable support for launching pyspark using ...
Merge branch 'master' of https://github.com/mesos/spark into commutative

Conflicts:
	core/src/main/scala/spark/RDD.scala
Remove RDD.coalesce default arguments.
Add back return types.
Merge pull request #453 from markhamstra/commutative

Change docs on 'reduce' since the merging of local reduces no longer pre...
Add commutative requirement for 'reduce' to Python docstring.
Fix JavaRDDLike.coalesce return type.
Merge pull request #457 from markhamstra/commutative

Add commutative requirement for 'reduce' to Python docstring.
Move JavaRDDLike.coalesce into the right places.
Merge pull request #452 from stephenh/misc

Add RDD.coalesce, clean up some RDDs, other misc.