Realtime updates

In order to do this either Django needs to have full async Python support or we would need to introduce separate service for pushing messages over websocket to clients. I don't want to add the latter, and former is up to Django team. But they are slowly getting there, so here's hope!

I am aware of deepstream as real time server for web apps, but maybe I could implement one in Python?

Also, realtime server should have a way to filter events before sending them to client, so we can verify if user can see replied thread before we tell them "oh yeah, thread 2137 got new reply".