YARN-1378. Implemented a cleaner of old finished applications from the RM state-store. Contributed by Jian He.
svn merge --ignore-ancestry -c 1548990 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1548991 13f79535-47bb-0310-9956-ffa450edef68