merge MAPREDUCE-5079 from trunk. Changes job recovery to restore state directly from job history, instaed of simulating state machine events. Contributed by Jason Lowe and Robert Parker.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1466770 13f79535-47bb-0310-9956-ffa450edef68