YARN-1254. Fixed NodeManager to not pollute container's credentials. Contributed by Omkar Vinit Joshi.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1529382 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-YAHOO-253-trunk-gd