MAPREDUCE-4463. Fix job recovery failures which were caused by HDFS permission issues since the token file was being read as the user who submitted the job rather than JobTracker user. Contributed by Tom White & Arun C Murthy.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1464514 13f79535-47bb-0310-9956-ffa450edef68