Bug 1049916 - Create Firefox Accounts smoke tests to validate user authe...

...ntication R=spenrose
I've created two testcase:  
(1) fxa_thru_uitest_test.js  - to test FxA authentication user flow from end-to-end with one app (UITest).  
(2) fxa_launch_test.js - to test launching FxA from a variety of FxA-consuming apps up to the first screen