rejiggering the cache for groupBy and select
Merge branch 'master' into rejigger-cache

Conflicts:
	pom.xml
address code review comments
update pom and fix broken UT
fix doc
Merge pull request #638 from metamx/rejigger-cache

Rejiggering the cache
Merge branch 'master' of github.com:metamx/druid into cleanup-ingest