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?
I think that they do not. We should probably add an issue to show a nice message to the user in this case.