Add StandardCodec that takes a standard Ruby encoder (like JSON)

E.g. StandardCodec.new(JSON) will do JSON.dump(message) and JSON.load(str)
Remove some dead code in Codec
Make the example a little more like an example
Change Server#handle_message to take only the message and the peer
Add documentation to the simple example
Add binfiles for the simple example
Add a readme for the simple example
Move the simple example to examples/simple_rpc
Rename SimpleServer and SimpleClient SimpleRpc*
Ad Yard
Add docs to Codec
Mark Peer and ClientPeer as private
Call #to_s on the thing returned from Codec#encode_message

Should probably add a test for this…
Fix a copy-paste bug in Codec

The original codec had a 5 byte header, it now uses 6 bytes.
Add an invariant test to the Codec tests.

I.e. decode(encode(msg)) == msg and encode(decode(frame)) == frame
Add docs for Codec
Include docs about protected methods
Add docs for Server
Rename Server#handle_message #handle_request

Peers handle messages, servers handle requests
Add logging to Server