Changed method name of createReceiver to getReceiver as it is not intended to be a factory.
Plug in actor as stream receiver API
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.