Union query fix

fix broken CombiningSequence.toYielder behavior

fix jetty threads getting stuck

Fix Jetty threads getting stuck on exceptions

remove initial delay from polling

remove initial delay from polling in coordinator, this will help in the
cases when the pollDuration is set to higher than coordinator
startDelay.

This reverts commit 76437379, reversing
changes made to 79e6d4eb.

Conflicts:
	pom.xml

Refactor and clean-up Druid data ingestion Part 1 (The Schemas)

Conflicts:
	indexing-hadoop/src/main/java/io/druid/indexer/HadoopDriverConfig.java
	indexing-hadoop/src/main/java/io/druid/indexer/HadoopDruidIndexerConfig.java
	indexing-hadoop/src/main/java/io/druid/indexer/HadoopDruidIndexerConfigBuilder.java
	pom.xml
	server/src/main/java/io/druid/segment/realtime/RealtimeManager.java
	server/src/main/java/io/druid/segment/realtime/firehose/EventReceiverFirehoseFactory.java

Multithread costbalancer

Support null values in DimExtractionFn in topN and groupBy

Union query source

remove toShortString
minor other changes