YARN-1080. Improved help message for "yarn logs" command. Contributed by Xuan Gong.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1518731 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5483. revert MAPREDUCE-5357. (rkanter via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1518772 13f79535-47bb-0310-9956-ffa450edef68