HDFS-4850. Fix OfflineImageViewer to work on fsimages with empty files or snapshots. Contributed by Jing Zhao.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1490080 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4053. Move the jira description to release 2.1.0 section

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1490085 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9593. Changing CHANGES.txt to reflect merge to branch-2.1-beta.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1490105 13f79535-47bb-0310-9956-ffa450edef68