Merge change 1541718 from trunk: Move HDFS-5325 and HDFS-5488 from BUG-FIX to IMPROVEMENT in CHANGES.txt.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1541719 13f79535-47bb-0310-9956-ffa450edef68