HDFS-2857. Merge r1238747 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1492890 13f79535-47bb-0310-9956-ffa450edef68
HDFS-3009. Merge r1293390 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1492892 13f79535-47bb-0310-9956-ffa450edef68
HDFS-3792. Merge r1372690 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1492894 13f79535-47bb-0310-9956-ffa450edef68
YARN-773. Moved YarnRuntimeException from package api.yarn to api.yarn.exceptions. Contributed by Jian He.
svn merge --ignore-ancestry -c 1492903 ../../trunk/


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YARN-692. Creating NMToken master key on RM and sharing it with NM as a part of RM-NM heartbeat. Contributed by Omkar Vinit Joshi.
svn merge --ignore-ancestry -c 1492907 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1492908 13f79535-47bb-0310-9956-ffa450edef68
HDFS-3163. Merge r1338486 from trunk

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HDFS-4659. Merge r1477994 from trunk

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