YARN-24. Nodemanager fails to start if log aggregation enabled and namenode unavailable. (sandyr via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1461892 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9357. Fallback to default authority if not specified in FileContext. Contributed by Andrew Wang


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1461901 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd
Merge remote branch 'origin/branch-2-gd' into fb-YARN-474-branch-2-gd