Routing email confirmation back to Lockwise

[changecourse]

Users in our UR sessions were very confused to go through the FxA Auth process, only to land in either Safari or Firefox iOS after confirming their email address.

Pending the completion of OAuth... depends on #242

Decide on a better approach for email confirmation, so a user isn't "dead-ended" within Safari or Firefox iOS, ideally routing a user via link in email back to the app.

This may need to be tied to FxA efforts if it needs to be handled on their end, but placing within our repo for now so we can track against it.

[sandysage]

Includes the scope in #62

[sandysage]

@irrationalagent is there a way to tell the drop off rate that exists from the email flow versus the code flow? Should we open a bugzilla ticket to find this out?

[irrationalagent]

see here. looks like performance is pretty much the same so far.