Merge r1528632 from trunk to branch-2 for YARN-1141. Updating resource requests should be decoupled with updating blacklist (Zhijie Shen via bikas)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1528640 13f79535-47bb-0310-9956-ffa450edef68