Mark HADOOP-8691 in CHANGES.txt as incompatible changes.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1575381 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5986. Capture the number of blocks pending deletion on namenode webUI. Contributed by Chris Nauroth.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1575384 13f79535-47bb-0310-9956-ffa450edef68