Reorganize into two main namespaces: lib and internal

[EliAndrewC]

We're inconsistent about how our code is structured. We decided awhile back that we'd like to eventually end up with all of the stuff that plugins should import under sideboard.lib and almost everything else under sideboard.internal but we've only put some of our stuff in sideboard.internal, leaving out:

• config.py (which I think is not under internals because of some import issue, maybe)
• jsonrpc.py
• server.py
• websockets.py