YARN-443. allow OS scheduling priority of NM to be different than the containers it launches (tgraves)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1454411 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4567. Webhdfs does not need a token for token operations. Contributed by Daryn Sharp.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1454460 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd