BREAKDOWN OF HDFS-2832 ENABLE SUPPORT FOR HETEROGENEOUS STORAGES IN HDFS

IMPROVEMENTS:

    HDFS-4985. Add storage type to the protocol and expose it in block report
    and block locations. (Arpit Agarwal)
    
    HDFS-5115. Make StorageID a UUID. (Arpit Agarwal)

    HDFS-5000. DataNode configuration should allow specifying storage type.
    (Arpit Agarwal)

    HDFS-4987. Namenode changes to track multiple storages per datanode.
    (szetszwo)

    HDFS-5154. Fix TestBlockManager and TestDatanodeDescriptor after HDFS-4987.
    (Junping Du via szetszwo)

    HDFS-5009. Include storage information in the LocatedBlock.  (szetszwo)

    HDFS-5134. Move blockContentsStale, heartbeatedSinceFailover and
    firstBlockReport from DatanodeDescriptor to DatanodeStorageInfo; and
    fix a synchronization problem in DatanodeStorageInfo.  (szetszwo)