HBaseRpcMetrics is now logging a WARN message every time it encounters an
unregistered RPC method.
In my case I now get huge log files filled with these warnings because the
hbase-trx transactional extension of HBase uses a subclass of HRegionServer
that adds new interface methods.
It's easy enough to tell log4j to ignore HBaseRpcMetrics output.
However, it would be nice if the Server/HRegionServer HBaseRpcMetrics
mechanism was more extensible so I could pass down new interfaces or grab
the HBaseRpcMetrics from the HBaseRPC object to add interfaces from up