svn merge -c 1581437 from trunk for HADOOP-10426. Declare CreateOpts.getOpt(..) with generic type argument, removes unused FileContext.getFileStatus(..) and fixes various javac warnings.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1581440 13f79535-47bb-0310-9956-ffa450edef68