HDFS-5236. Change PathBasedCacheDirective APIs to be a single value rather than batch. (Contributed by Andrew Wang)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-4949@1525183 13f79535-47bb-0310-9956-ffa450edef68
Delete a file for HDFS-5236.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-4949@1525184 13f79535-47bb-0310-9956-ffa450edef68