Add Login Link to Email option

[EdwardHinkle]

When using the email option for authentication, it would be useful to include a url that when clicked would open IndieAuth.com with the verification code inside the url, this would prevent a user from having to copy and paste the verification code from the email client to the web browser and make it much more mobile user friendly. The verification code would instantly be used, removed from use as a verification code and the user redirected to the origin url.

[aaronpk]

I did some experiments today of using Google's Email Actions API to make a button you can press from within Gmail/Inbox so that you don't even have to open a browser to finish signing in!