[Reviewer: Rob] I-CSCF in Homestead (sto581)

The UTs aren't particularly extensive, but I'm not sure how much they really add. I also couldn't work out how to get findFirstAVP (or any call) to return different values on different calls in the mock setup. If that makes any sense. So yeh, I can add more UTs if you think necessary and you help me with that.

I've done a reasonable amount of live testing and I'm confident it's working as per your spec.

EDIT - I've pushed a second commit which now has extensive UTs.

UPDATE - I've applied the mark ups and integrated with Matt's new code. Rob, do you want to have a second look at this?