YARN-617. Made ContainerTokens to be used for validation at NodeManager also in unsecure mode to prevent AMs from faking resource requirements in unsecure mode. Contributed by Omkar Vinit Joshi.
Merge from trunk revision 1483667 with little test modifications for proper merge.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1483668 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd
Merge remote branch 'origin/branch-2-gd' into fb-HADOOP-7435-branch-2-gd