HDFS-5615: stubbing a few things
HDFS-5613. NameNode: implement handling of ACLs in combination with symlinks. Contributed by Chris Nauroth.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-4685@1559804 13f79535-47bb-0310-9956-ffa450edef68
Merge branch 'HDFS-4685' into HDFS-4685-WIP
Merge branch 'HDFS-4685' into HADOOP-10241
Merge branch 'HDFS-4685' into HDFS-5799
Merge branch 'HDFS-4685' into HDFS-5615
Merge branch 'HDFS-5615' into HDFS-4685-WIP
Merge branch 'HDFS-5799' into HDFS-4685-WIP
Merge branch 'HADOOP-10241' into HDFS-4685-WIP