[RPC] Add a RPC Processor
[RPC] Do not send the old Message's body

The body is useless in the new messqge's body, as this messqge is just a signal acknowledging the client the process is done
[RPC] Returns the result of the nested processor
[RPC] Rename RPC Processor to RPC Server Processor
[RPC] Add a RPC Client Processor
[RPC] Rather than sending an empty message, send a config value instead
[RPC] Use a correct prefix for the RPC Client options
[RPC] Add a README
[RPC] Add a test case for the RpcServerProcessor
[RPC] Add some tests for the RPC Client processor