svn merge -c 1498665 Merging from trunk to branch-2 to fix HDFS-4888.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1498672 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9414.  Refactor out FSLinkResolver and relevant helper methods.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1498728 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9676.  Make maximum RPC buffer size configurable (Colin Patrick McCabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1498740 13f79535-47bb-0310-9956-ffa450edef68