YARN-1117. Improved help messages for "yarn application" and "yarn node" commands. Contributed by Xuan Gong.
svn merge --ignore-ancestry -c 1519117 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1519119 13f79535-47bb-0310-9956-ffa450edef68