[WIP] Add tests

[simison]

Work in progress:

• Add Karma test runner
• Refactor injected interceptor to a separate service (requestService) for easier testing
• Test that injecting said service works
• Test that authService can be initialised
• Test that httpBuffer can be initialised
• 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
• 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