merge YARN-579 from trunk. Stop setting the Application Token in the AppMaster env, in favour of the copy present in the container token field. Contributed by Vinod Kumar Vavilapalli.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1471815 13f79535-47bb-0310-9956-ffa450edef68