YARN-561. Modified NodeManager to set key information into the environment of every container that it launches. Contributed by Xuan Gong.
MAPREDUCE-5175. Updated MR App to not set envs that will be set by NMs anyways after YARN-561. Contributed by Xuan Gong.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1471207 13f79535-47bb-0310-9956-ffa450edef68