MAPREDUCE-4949. Enable multiple pi jobs to run in parallel. (sandyr via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1437029 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-4946. Fix a performance problem for large jobs by reducing the number of map completion event type conversions. Contributed by Jason Lowe.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1437103 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9231. Parametrize staging URL for the uniformity of distributionManagement. Contributed by Konstantin Boudnik.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1437140 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9231. Add missing CHANGES.txt

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1437143 13f79535-47bb-0310-9956-ffa450edef68
YARN-277. Use AMRMClient in DistributedShell to exemplify the approach. Contributed by Bikas Saha

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