Tell asyncio which is the current event loop

[Matbj]

Solves #299

[carltongibson]

I'll test this but I strongly suspect it will lead to the exact issue in django/channels#1374, which prompted the change in Daphne, after consultation with Folks Who Know™.

As per comment on #299, I think we're in a half-way land at the moment, and we need to be passing the running loop to Lock (using asyncio.get_running_loop()) until Lock.__init__() stops using get_event_loop() itself.

[carltongibson]

Closing as per ticket