YARN-1357. Merging change r1537293 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1537296 13f79535-47bb-0310-9956-ffa450edef68
YARN-1358. Merging change r1537305 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1537307 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5065. Merging change r1537319 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1537320 13f79535-47bb-0310-9956-ffa450edef68
YARN-1321. Changed NMTokenCache to support both singleton and an instance usage. Contributed by Alejandro Abdelnur.
svn merge --ignore-ancestry -c 1537334 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1537335 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