HDFS-4540. Merge 1453025 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1453030 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4519. Merge change 1453050 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1453051 13f79535-47bb-0310-9956-ffa450edef68
YARN-227. Application expiration difficult to debug for end-users (Jason Lowe via jeagles)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1453087 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5027. Shuffle does not limit number of outstanding connections (Robert Parker via jeagles)

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