MAPREDUCE-5131. Fix handling of job monitoring APIs during JobTracker restart. Contributed by Arun C. Murthy.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1465171 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5129. Allow tags to JobHistory for deeper analytics. Contributed by Billie Rinaldi.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1465191 13f79535-47bb-0310-9956-ffa450edef68