HDFS-5900. Cannot set cache pool limit of unlimited via CacheAdmin. Contributed by Andrew Wang.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1565843 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5882. TestAuditLogs is flaky (jxiang via cmccabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1565848 13f79535-47bb-0310-9956-ffa450edef68
YARN-1672. YarnConfiguration is missing a default for yarn.nodemanager.log.retain-seconds (Naren Koneru via kasha)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1565867 13f79535-47bb-0310-9956-ffa450edef68
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