Headless server/desktop app

Umbrella ticket for sponsor 1, objective 5.

Outstanding Tasks:

• add command line options for things like controlling log verbosity, port to bind to, etc.
• research better input validation options
• unit tests for all controllers
• REST API authentication with bearer token (maybe optional, or only when not bound to localhost?)
• Websocket API authentication (problematic since JavaScript can't control headers in request)
• simple API documentation in README.md
• add support for adding contacts (blocked by missing support in core)