Subquery support for GroupBy queries
Merge branch 'master' into subquery
Fix subquery merge issues
Fix NPE when subquery returns empty result
Documentation for query data sources
Merge branch 'master' into subquery
Merge branch 'master' into subquery
Fixed realtime querying after subquery changes
Merge branch 'master' into subquery
Extra null value check. Not sure why this is needed in the subquery implementation and not regular queries. Bug elsewhere?
Merge branch 'master' into subquery
Fixed realtime index query serving failure due to incorrect treatment of DataSource
Blocking Executors and maxPendingPersists, oh my!

- Execs.newBlockingSingleThreaded can now accept capacity = 0.
- Changed default maxPendingPersists from 2 to 0.
- Fixed serde of maxPendingPersists in RealtimeIndexTasks.
Merge pull request #419 from metamx/mpp

Blocking Executors and maxPendingPersists, oh my!
fix populateCache flag not working
cosmetics
add CachingClusteredClient tests
add disable populate / use cache tests
port hyperunique to open source
add headers