YARN-1717. Enabled periodically discarding old data in LeveldbTimelineStore. Contributed by Billie Rinaldi.
svn merge --ignore-ancestry -c 1577693 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1577695 13f79535-47bb-0310-9956-ffa450edef68
svn merge -c 1577692 FIXES: MAPREDUCE-5570. Map task attempt with fetch failure has incorrect attempt finish time. Contributed by Rushabh S Shah


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1577696 13f79535-47bb-0310-9956-ffa450edef68