update hadoop dependency to 2.4.0
Merge remote-tracking branch 'origin' into yingdac_updatehadoop_846
remove unused line in testGetEvaluatorList
Move REEFFileNames ahead of HADOOP classpath entries
Merge pull request #920 from dafrista/bcho_change_yarn_classpath

Move REEFFileNames ahead of HADOOP classpath entries
netty4 only changes (w/o MLSS stuff)
minor refactoring in groupcomm operators
Merge remote-tracking branch 'origin' into yingdac_updatehadoop_846
use the KeepContainersAcrossApplicationAttempts=true for driver submission, so that we can keep evaluators running when driver crashes
Closing #930: Add Idempotent annotation.

Also updating the license headers.
Closing #932: A .toString for JobMessage
Merge pull request #939 from Microsoft-CISL/weimer_930

Closing #930: Add Idempotent annotation.
Merge pull request #940 from Microsoft-CISL/weimer_932

Closing #932: A .toString for JobMessage
Merge pull request #847 from Microsoft-CISL/yingdac_updatehadoop_846

update hadoop dependency to 2.4.0
add a recovery flag to proto to indicates communications from orphan evaluators for recovery
minor format change and bug fixing
remove unnecessary hasRecovery check
undo mutable evaluatorId change
Adding thread names to the EvaluatorMessageDispatcher

Closes #936. `EvaluatorMessageDispatcher` now names the threads spawned with the ID of the Evaluator events are dispatched for.
Merge pull request #916 from Microsoft-CISL/juwang-httptestfix

juwang-remove unused line in testGetEvaluatorList