Added tests for testing network input stream.
Minor fixes.
Added tests for the file input stream.
Merge remote-tracking branch 'public/master' into dev

Conflicts:
	core/src/main/scala/spark/BlockStoreShuffleFetcher.scala
	core/src/main/scala/spark/KryoSerializer.scala
	core/src/main/scala/spark/MapOutputTracker.scala
	core/src/main/scala/spark/RDD.scala
	core/src/main/scala/spark/SparkContext.scala
	core/src/main/scala/spark/executor/Executor.scala
	core/src/main/scala/spark/network/Connection.scala
	core/src/main/scala/spark/network/ConnectionManagerTest.scala
	core/src/main/scala/spark/rdd/BlockRDD.scala
	core/src/main/scala/spark/rdd/NewHadoopRDD.scala
	core/src/main/scala/spark/scheduler/ShuffleMapTask.scala
	core/src/main/scala/spark/scheduler/cluster/StandaloneSchedulerBackend.scala
	core/src/main/scala/spark/storage/BlockManager.scala
	core/src/main/scala/spark/storage/BlockMessage.scala
	core/src/main/scala/spark/storage/BlockStore.scala
	core/src/main/scala/spark/storage/StorageLevel.scala
	core/src/main/scala/spark/util/AkkaUtils.scala
	project/SparkBuild.scala
	run
Merge branch 'dev' of github.com:radlab/spark into dev
Added save operations to DStreams.
Bump required Py4J version and add test for large broadcast variables.
Fix PySpark hash partitioning bug.

A Java array's hashCode is based on its object
identify, not its elements, so this was causing
serialized keys to be hashed incorrectly.

This commit adds a PySpark-specific workaround
and adds more tests.
Modified RDD API to make dependencies a var (therefore can be changed to checkpointed hadoop rdd) and othere references to parent RDDs either through dependencies or through a weak reference (to allow finalizing when dependencies do not refer to it any more).
BlockManager UI.
code Formatting
Nicer storage level format on RDD page
Added checkpointing support to all RDDs, along with CheckpointSuite to test checkpointing in them.
Added 'synchronized' to RDD serialization to ensure checkpoint-related changes are reflected atomically in the task closure. Added to tests to ensure that jobs running on an RDD on which checkpointing is in progress does hurt the result of the job.
Fixed serialization bug in countByWindow, added countByKey and countByKeyAndWindow, and added testcases for them.
Merge branch 'dev-checkpoint' into dev
Made checkpointing of dstream graph to work with checkpointing of RDDs. For streams requiring checkpointing of its RDD, the default checkpoint interval is set to 10 seconds.
Fixed major bugs in checkpointing.
Made more bug fixes for checkpointing.
Added a few more comments to the checkpoint-related functions.