Test with Mocha with Chai, run with Gulp

+ Use `q-io/http` instead of `request` as HTTP request module for tests
  to that we can easily use promises
+ Use Mocha and Chai as test framework to harness all that
  expectational, organizational and reporting sweetness
+ Run these tests with Gulp. My first time trying Gulp; so far I'm
  impressed, but this isn't far in yet.

Note: The Gulp task is not yet starting and stopping the service, which
it should do so you don't have to start it manually separately from the
API tests. But that's work for a future commit. Progress! Yes!