Make configurable number of concurrent requests to Content API in Facia Press

Also some clean up of the code that does the retrievals, it was a bit mystifying :stars: 

The idea is that we can reduce this on dev boxes and actually run Facia Press without its constantly timing out :-1: 
It'd be really unlikely to fail ... though I do take your point. Maybe we should just delete these test cases - I'm not really sure how else we can test the concurrency though.