Initial checkin of the lightbox API.

* Bring over lots of the grunt infrastructure from fxa-js-client
Add more tests around requierd options. Split out some helper functions into their own modules.
Set up for travis tests.

Only enable Firefox 18 for now.
Enable all the browsers, but only one Firefox.
Add YUIDoc docs. Create the FxaRelierClient with a clientId as a required parameter.
call Lightbox.load with the URL to load.
Try to add more tests to the FxaRelierClient. Break up the initialization of the lightbox api
Add `force_email` to signin. Add more unit tests to the lightbox API to ensure the lightbox is opened to the correct page and that results/errors are propagated.
Add the redirect flow.
Extract common authentication API functions to a common class, AuthenticationAPI
Subclasses of AuthenticationAPI only have to worry about overriding `openFxa`
No need for events and function helpers, we only support IE9+ which already do the right thing.
Merge pull request #3 from mozilla/initial-version

Initial checkin of the lightbox/redirect APIs.

r=zaach, 6a68