Move HDFS-5538, HDFS-5545, HDFS-5536, HDFS-5312, and HDFS-5629 from trunk to 2.4.0 section.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1551724 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5197. Add a service for checkpointing task state.
Contributed by Carlo Curino


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1551726 13f79535-47bb-0310-9956-ffa450edef68
YARN-1028. Added FailoverProxyProvider capability to ResourceManager to help with RM failover. Contributed by Karthik Kambatla.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1551739 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5189. Add policies and wiring to respond to preemption requests
from YARN. Contributed by Carlo Curino.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1551748 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5687. Fixed failure in TestYARNRunner caused by YARN-1446. Contributed by Jian He.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1551774 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5674. Editlog code cleanup: remove @SuppressWarnings("deprecation") in FSEditLogOp; change FSEditLogOpCodes.fromByte(..) to be more efficient; and change Some fields in FSEditLog to final.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1551812 13f79535-47bb-0310-9956-ffa450edef68