decouple sending emails from model. This now means we can override
the logic that sends the email without creating a bunch of code just
to avoid creating new tables when we subclass the EmailConfirmation class
this makes me happy
move the logic for sending email confirmations to here.
decouple the sending of emails, override settings.ACCOUNT_EMAIL_SENDER_CALLBACK with a dotted path to the function responsible for sending emails. look at account.callbacks.send_rendered_email for the default callback.