[WIP] Add tests

[simison]

Work in progress:

• [x] Add Karma test runner
• [x] Refactor injected interceptor to a separate service (requestService) for easier testing
• [x] Test that injecting said service works
• [ ] Test that authService can be initialised
• [ ] Test that httpBuffer can be initialised
• [x] Test that invoking loginConfirmed and loginCancelled broadcasts events
• [ ] Test that invoking loginConfirmed and loginCancelled broadcasts events with data
• [ ] Test that httpBuffer's methods retryAll, rejectAll, and append work
• [x] Test that everything works via $http using (mock using $httpBackend)

Not sure when I'll have time next time with this, so if anyone feels like continuing from here, do it! :-)

[simison]

Ah, damn, noticed only now #69 — will look into combining these.

[simison]

Included event tests by @nils-wisiol from #69