YARN-2051. Fix bug in PBimpls and add more unit tests with reflection. (Contributed by Binglin Chang)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1615025 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6798. Add test case for incorrect data node condition during balancing. (Contributed by Benoy Antony)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1615044 13f79535-47bb-0310-9956-ffa450edef68