Add a new DataTransferProtocol operation, Op.TRANSFER_BLOCK, instead of using RPC

org.apache.hadoop.hdfs.server.datanode.ReplicaNotFoundException: 65536 = numBytes < visible = 90564, r=ReplicaInPipeline, blk_8440021909252053811_1001, TEMPORARY
  getNumBytes()     = 65536
  getBytesOnDisk()  = 0
  getVisibleLength()= -1
  getVolume()       = /grid/0/hudson/hudson-slave/workspace/PreCommit-HDFS-Build/trunk/build/test/data/dfs/data/data3/current/finalized
  getBlockFile()    = /grid/0/hudson/hudson-slave/workspace/PreCommit-HDFS-Build/trunk/build/test/data/dfs/data/data3/tmp/blk_8440021909252053811
  bytesAcked=0
  bytesOnDisk=0
	at org.apache.hadoop.hdfs.server.datanode.FSDataset.convertTemporaryToRbw(FSDataset.java:1383)
	at org.apache.hadoop.hdfs.server.datanode.DataNode.convertTemporaryToRbw(DataNode.java:2023)
	at org.apache.hadoop.hdfs.server.datanode.TestTransferRbw.testTransferRbw(TestTransferRbw.java:121)