Bug 1047130 - Implement desktop backend to login to FxA via OAuth for Loop. r=vladikoff,ckarlof,mikedeboer

This implements the OAuth authorization phase.
Bug 1052174 - Applied -moz-resolution fragment to favicons to enable support for high resolution throughout the UI. r=MattN
Bug 1054712 - Remove duplicate logic from tabbrowser and search bar by using the getImageURLForResolution helper function in PlacesUtils. r=MattN