svn merge -c 1501841. Merging from trunk to branch-2 to fix HDFS-4887.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1501843 13f79535-47bb-0310-9956-ffa450edef68
YARN-368. Fixed a typo in error message in Auxiliary services. Contributed by Albert Chu.
svn merge --ignore-ancestry -c 1501852 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1501853 13f79535-47bb-0310-9956-ffa450edef68
YARN-295. Fixed a race condition in ResourceManager RMAppAttempt state machine. Contributed by Mayank Bansal.
svn merge --ignore-ancestry -c 1501856 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1501857 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4969. WebhdfsFileSystem expects non-standard WEBHDFS Json element. (rkanter via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1501870 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd
Merge remote branch 'origin/branch-2-gd' into fb-MAPREDUCE-4884-branch-2-gd