Possible solution for #6

Turns `http://steamcommunity.com/openid/id/930561197961093972@steam.com` to `49f68a5c8493ec2c0bf489821c21fc3b@steam.com` when generating an email address for a user's profile if `$user_profile->identifier.'@'.$provider_code.'.com'` doesn't pass `cot_check_mail()`

Other possible solutions I can think of:
- Generate a hash only for email address for auto-register accounts and if auto-register isn't on, force the user to provider an email address if `$user_profile->identifier.'@'.$provider_code.'.com'` doesn't pass `cot_check_email()`
- Generate a hash only for email address for auto-register accounts