Reverting patches from branch-2.3 to help address stabilization issues.
    Reverting YARN-1493.
    Reverting YARN-1490.
    Reverting YARN-1041
    Reverting YARN-1166.
    Reverting YARN-1566.
    Reverting YARN-1689.
    Reverting YARN-1661.
Updated CHANGES.txt entry also to exlude these patches.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.3@1565792 13f79535-47bb-0310-9956-ffa450edef68