Upgrade config.json

[marzavec]

The config.json file is a simple json configuration that is served from the same directory as the chat client. This is dynamically loaded in the hackchat-engine and specifies what path the websocket should be loaded through. This allows people who are hosting a hack chat instance to easily specify their own server, without having to dig through source and recompile the chat client.

Adding other customization options to this file may be nice. For instance a 'banner' or 'title' field to allow further customization.

It may also be handy to add a 'version' field to ensure the client is up-to-date and not running a cached version.