HDFS-5794. Fix the inconsistency of layout version number of ADD_DATANODE_AND_STORAGE_UUIDS between trunk and branch-2. Contributed by Jing Zhao.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1559209 13f79535-47bb-0310-9956-ffa450edef68