Bringing into 0.96 as blocker

Upping priority on this since what is there doesn't make much sense in new pb context (and versioning is done w/ Writables which we are trying to purge).

Assigning it to myself. Will get to it.

Unassigning from myself. From the dev mailing list, it seems like stack is already involved in refining the proposal.

This patch has hackup to make MasterProtocol, the isMasterRunning method,
work by hooking up the generated protobuf Service to our rpc.
It also messes with TestProtoBufRpcServer test class hooking up
a "protocol" to use protobuf Services instead. It does not remove
VersionedProtocol though it is being bypassed in this patch. We do
not remove it because it would bulk up the patch.

• MasterAdminProtocol
• MasterMonitorProtocol
  Remove code copied from generated protobuf BlockingInterface
• MasterProtocol removed; just use the generated pb Interface instead.
• HConnectionManager This class has some hackery making the call
  isMasterRunning. Instead of asking HBaseClientRPC for a proxy,
  we instead ask for a pb RpcChannel so we can make a Stub for the
  client to use. The RpcController goes unused/unexploited.
• HBaseClient Allow for now a 'null' proxy. This is how we indicate
  a protobuf Service. Would need to be fixed so we pass actual
  Service name.
• ProtobufRpcClientEnging We make a BlockingRpcChannel. Knows
  how to do the call against the server. Added a getChannel
  call which is like doing a getProxy. Refactored call to
  use the stub if present. Why we have interfaces and protocol?
  Seems broke. Needs cleanup.
• TestProtoBufRpc Pulled this test around to mess with
  protobuf Service.

Here are some notes I've been keeping while working on this issue: https://docs.google.com/document/pub?id=1WCKwgaLDqBw2vpux0jPsAu2WPTRISob7HGCO8YhfDTA

I put this 'experiment' up on rb: https://reviews.apache.org/r/8790/

This issue has some relation to this one

Resolving as 'Invalid'. We will handle versioning by not doing versioning (See HBASE-7479 where we strip what versioning we currently had).