Changed method of publishing segment ownership to ZK to use batching, includes changes to allow for migration

Conflicts:
	client/src/main/java/com/metamx/druid/QueryableNode.java

Cleanup znodes left behind by announcer

1) Adjust the Announcer to cleanup parent nodes that it creates.  This stops it from leaving little turdlings lying around on zookeeper as nodes exit
2) Rename *CuratorDataSegmentAnnouncer because neither of them depend directly on Curator.

Adding a RabbitMQFirehoseFactory implementation