HADOOP-9355. Abstract Symlink tests to use either FileContext or FileSystem (Andrew Wang via Colin Patrick McCabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1496690 13f79535-47bb-0310-9956-ffa450edef68
YARN-874. Making common RPC to switch to not switch to simple when other mechanisms are enabled and thus fix YARN/MR test failures after HADOOP-9421. Contributed by Daryn Sharp and Vinod Kumar Vavilapalli.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1496692 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-HDFS-4310-trunk-gd