Merge pull request #4 from VolkerBb/master

swift 3.1 changes

removed bogus comment

Add Dispatch to Tests

Add Dispatch

bug fixes & cosmetics, better queue defaulting

- pass ‘on’ argument through to BasicPromise
- add a hook to change the default queue

Ensure bug fix is pickec up

Fixed bug in Promise.then

removed unneeded constructors from BasicPromise

more cleanups

PromiseKit-style protocol for Result

factored defaultQ for debugging, rm AlreadyError

Swift was crashing!