remove unused isForceAuth
Create the Redirect and WebChannel Brokers. Get rid of the Redirect Channel. Move the functionality relating to the WebChannel from ServiceMixin to the WebChannelBroker.
Move more WebChannel functionality from Channels.js to WebChannel
Push FxaDesktop related code from fxa-client to the FirefoxDesktopBroker.
Remove the Channels abstraction, it is now taken care of by the Brokers
fix web channel verification.