Make prodsys more real-time using websockets.

[haakenlid]

Currently prodsys data is only pulled when the client actively sends requests to the api. Look into if this causes problems if people try to work on the same story at the same time.

Maybe just expose a single event stream on a websocket, that includes patches, or just id / timestamps, so that the client can know which content is stale and must be reloaded with a get request to the api.