HDFS-4651. Offline Image Viewer backport to branch-1. Contributed by Chris Nauroth.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1462875 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4651. Adding missed files in the previous commit.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1462876 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4651. Adding missed CHANGES.txt in the previous commit.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1462878 13f79535-47bb-0310-9956-ffa450edef68