Changed method name of createReceiver to getReceiver as it is not intended to be a factory.
Plug in actor as stream receiver API
Changed method name of createReceiver to getReceiver as it is not intended to be a factory.
actor as receiver
Improved document comment in example
Taking FeederActor out as seperate program
Added an initial spark job to ensure worker nodes are initialized.
Fixed bug in CheckpointRDD to prevent exception when the original RDD had zero splits.
Fixed bugs in FileInputDStream and Scheduler that occasionally failed to reprocess old files after recovering from master failure. Completely modified spark.streaming.FailureTest to test multiple master failures using file input stream.
Changed scheduler and file input stream to fix bugs in the driver fault tolerance. Added MasterFailureTest to rigorously test master fault tolerance with file input stream.
Added filter functionality to reduceByKeyAndWindow with inverse. Consolidated reduceByKeyAndWindow's many functions into smaller number of functions with optional parameters.
Changes functions comments to make them more consistent.
Removed countByKeyAndWindow on paired DStreams, and added countByValueAndWindow for all DStreams. Updated both scala and java API and testsuites.
Added TwitterInputDStream from example to StreamingContext. Renamed example TwitterBasic to TwitterPopularTags.
Moved Java streaming examples to examples/src/main/java/spark/streaming/... and fixed logging in NetworkInputTracker to highlight errors when receiver deregisters/shuts down.
Made MasterFailureTest more robust.
Many changes to ensure better 2nd recovery if 2nd failure happens while
recovering from 1st failure
- Made the scheduler to checkpoint after clearing old metadata which
  ensures that a new checkpoint is written as soon as at least one batch
  gets computed  while recovering from a failure. This ensures that if
  there is a 2nd failure while recovering from 1st failure, the system
  start 2nd recovery from a newer checkpoint.
- Modified Checkpoint writer to write checkpoint in a different thread.
- Added a check to make sure that compute for InputDStreams gets called
  only for strictly increasing times.
- Changed implementation of slice to call getOrCompute on parent DStream
  in time-increasing order.
- Added testcase to test slice.
- Fixed testGroupByKeyAndWindow testcase in JavaAPISuite to verify
  results with expected output in an order-independent manner.
Added checkpointing and fault-tolerance semantics to the programming guide. Fixed default checkpoint interval to being a multiple of slide duration. Fixed visibility of some classes and objects to clean up docs.
Merge branch 'streaming' into ScrapCode-streaming

Conflicts:
	streaming/src/main/scala/spark/streaming/dstream/KafkaInputDStream.scala
	streaming/src/main/scala/spark/streaming/dstream/NetworkInputDStream.scala
Changed networkStream to socketStream and pluggableNetworkStream to become networkStream as a way to create streams from arbitrary network receiver.