Merge 1529068 from trunk to branch-2 for YARN-1131.  logs command should return an appropriate error message if YARN application is still running. Contributed by Siddharth Seth.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1529069 13f79535-47bb-0310-9956-ffa450edef68