MAPREDUCE-4810. Added new admin command options for MR AM. Contributed by Jerry Chen.
svn merge --ignore-ancestry -c 1430707 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1430708 13f79535-47bb-0310-9956-ffa450edef68