Added Websocket reconnection and global 401 error handling.

- Websocket will automatically reconnect ([with decay](https://github.com/joewalnes/reconnecting-websocket/blob/master/reconnecting-websocket.js#L66) for server happiness). 
- Any jQuery AJAX requests which return a `401` will cause the app to redirect to the root path.

@pdehaan r?
Not sure if we want to throw an informational `console.log()` up in here, but may be pointless if they don't persist across redirects in the developer tools.