Changes to allow pushing events directly to realtime tasks, and the creation
of single-segment realtime tasks.

Realtime:
- Move firehose stuff to com.metamx.druid.realtime.firehose package
- ClippedFirehoseFactory provides a time-clipped view
- TimedShutoffFirehoseFactory shuts off at a particular time

Indexer:
- Split StringInputRowParser into {String,Map}InputRowParser

Merger:
- Remove minTime in favor of clipped firehoses
- Add task executor servlet that can push events to EventReceivers
- Add EventReceivingFirehose that accepts events as an EventReceiver
Merger: Advertise event receivers through service discovery
EventReceiverFirehoseFactory: Move parse exceptions from hasMore to addAll
TaskStorageQueryAdapter: Fix getSameGroupMergedStatus for nonexistent tasks
IndexerCoordinatorResource: Return 404 with proper json for status not found
Merge branch 'master' into event-push

Conflicts:
	client/src/main/java/com/metamx/druid/initialization/Initialization.java
	examples/src/main/java/druid/examples/twitter/TwitterSpritzerFirehoseFactory.java
	index-common/src/main/java/com/metamx/druid/indexer/data/StringInputRowParser.java
	merger/src/main/java/com/metamx/druid/merger/common/task/RealtimeIndexTask.java
	merger/src/main/java/com/metamx/druid/merger/coordinator/http/IndexerCoordinatorNode.java
	merger/src/main/java/com/metamx/druid/merger/worker/executor/ExecutorNode.java
ExecutorMain: Fix args count
ServiceAnnouncer:
- Interface with two impls, Noop and Curator
- Used wherever fine services are advertised

Initialization:
- Don't automatically register with service discovery
- Add makeServiceAnnouncer, announceDefaultService methods
- Replace serviceInstance with makeServiceInstanceFactory
Move indexer zk paths to ZkPathsConfig
Merger: Replace EventReceivers with ChatHandlers

This allows task-related objects to create any http endpoint their little
hearts desire.
ChatHandler: Remove useless method, add docs
EventReceiverFirehoseFactory: Remove useless getHandlerId method
Merge pull request #134 from metamx/event-push

Event push