YARN-1635. Implemented a Leveldb based ApplicationTimelineStore. Contributed by Billie Rinaldi.
svn merge --ignore-ancestry -c 1565868 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1565869 13f79535-47bb-0310-9956-ffa450edef68