Add a context to force 2 pass algorithm for topNs

make timeline findOvershadowed a set

Snapshot coordinator state before running anything

fix BatchServerInventoryViewTest waitForSync() logic

Make tests pass with Java 8

changed the url for kafka wget (old one was 404)

make prioritized executor service listenable

fix race condition with merge and persist and sink adding

Conflicts:
	indexing-service/src/main/java/io/druid/indexing/common/task/IndexTask.java
	server/src/main/java/io/druid/segment/realtime/RealtimeManager.java
	server/src/main/java/io/druid/segment/realtime/plumber/RealtimePlumber.java

Replace Iterable with Sequence in CursorFactory

ObjectColumnSelector/JS aggregator support for multi-valued columns.

add comment for ignoring test and add test for thread stucking