HDFS-6409. Merging change r1596739 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1596740 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6433. Merging change r1596742 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1596745 13f79535-47bb-0310-9956-ffa450edef68
YARN-2017. Merged some of the common scheduler code. Contributed by Jian He.
svn merge --ignore-ancestry -c 1596753 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1596754 13f79535-47bb-0310-9956-ffa450edef68
YARN-2089. FairScheduler: QueuePlacementPolicy and QueuePlacementRule are missing audience annotations. (Zhihai Xu via kasha)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1596766 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6438. Merge r1596772 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1596773 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6423. Merge r1596774 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1596775 13f79535-47bb-0310-9956-ffa450edef68