Merge -c 1464947 from branch-1 to branch-1.2 to fix MAPREDUCE-4824. Provide a mechanism for jobs to indicate they should not be recovered on JobTracker restart. Contributed by Tom White and Arun C. Murthy.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.2@1464949 13f79535-47bb-0310-9956-ffa450edef68