HDFS-4817. Make HDFS advisory caching configurable on a per-file basis.  (Contributed by Colin Patrick McCabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1526961 13f79535-47bb-0310-9956-ffa450edef68
add file for HDFS-4817

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.1-beta@1526962 13f79535-47bb-0310-9956-ffa450edef68