HDFS-6677. Change INodeFile and FSImage to support storage policy ID.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-6584@1610525 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6670. Add block storage policy support with default HOT, WARM and COLD policies.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-6584@1610529 13f79535-47bb-0310-9956-ffa450edef68