Use WebSockets for Now Playing

[zachreizner]

Combing the /v1/now_playing and /v1/queue endpoints into a new WebSocket based endpoint. This would significantly reduce HTTP overhead because of the more efficient transport. Also, only data that matters (like the queue or volume changing) would need to be sent server to client. This would eliminate the request loop on the frontend which is just retrieving redundant data most of the time.

[kevinwang]

Issue number conflicts from merging two repos.