Merge branches 'subtract' and 'bettersplits' into bizo

* subtract:
  Add RDD.subtract.

* bettersplits:
  Update more javadocs.
  Tweak test names.
  Remove fileServerSuite.txt.
  Update default.parallelism docs, have StandaloneSchedulerBackend use it.
  Change defaultPartitioner to use upstream split size.

Conflicts:
	core/src/main/scala/spark/scheduler/cluster/StandaloneSchedulerBackend.scala
	core/src/test/scala/spark/ShuffleSuite.scala