YARN-2400: Addendum fix for TestAMRestart failure. Contributed by Jian He


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1617333 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6837. Code cleanup for Balancer and Dispatcher. Contributed by Tsz Wo Nicholas Sze.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1617337 13f79535-47bb-0310-9956-ffa450edef68