Fixed Akka system init priorities.
Fixed Akka system init priorities.

DefaultGraph will now still use a system stored inside the registry. I
still want to get rid of this global thing, but unfortunately it is
convenient here and seems to be the only memory-efficient way to do
logging from inside the vertices (without cluttering up the API by
passing loggers everywhere).

uzh/signal-collect,uzh/signal-collect,hicolour/signal-collect,mageru/signal-collect,hicolour/signal-collect,mageru/signal-collect