HDFS-4804. WARN when users set the block balanced preference percent below 0.5 or above 1.0. Contributed by Stephen Chu.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1480099 13f79535-47bb-0310-9956-ffa450edef68
Merge -r 1476394:1476395 from trunk onto branch-2. Fixes HDFS-2576.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1480135 13f79535-47bb-0310-9956-ffa450edef68
Merge -r 1477848:1477849 from trunk onto branch-2. Fixes HDFS-4778.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1480136 13f79535-47bb-0310-9956-ffa450edef68
HDFS-2576. Fixed some compilation issues. Affects only branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1480151 13f79535-47bb-0310-9956-ffa450edef68