Merge 1529069 from branch-2 to branch-2.1-beta 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-2.1-beta@1529071 13f79535-47bb-0310-9956-ffa450edef68