Move HADOOP-8469 and HADOOP-8470 to 2.1.0-beta in CHANGES.txt.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1488873 13f79535-47bb-0310-9956-ffa450edef68
Move node group block placement JIRAs to 2.1.0-beta in CHANGES.txt.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1488874 13f79535-47bb-0310-9956-ffa450edef68