HDFS-5650. Remove AclReadFlag and AclWriteFlag in FileSystem API. Contributed by Haohui Mai.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-4685@1550256 13f79535-47bb-0310-9956-ffa450edef68
Merge branch 'HDFS-4685' into HDFS-5595
HDFS-5595: reintroduce an Acl class on the HDFS side.