YARN-1333. Support blacklisting in the Fair Scheduler (Tsuyoshi Ozawa via Sandy Ryza)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1535902 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd