{Reviewer: Andy} Add ISC tests based on Quaff

Andy, can you review this? This adds a way to use Quaff within clearwater-live-test (by writing a Quaff lambda to do what you want and appending it to t.quaff_lambdas), and adds some terminating AS tests.

I've verified with snoop that the ACK and the BYE come from Bono, and that the 200 OK goes to it, but I don't think I can test that programmatically (as this might run against an AIO node where sprout and bono have the same IP).