Feature/move _send_email_verification to models.profile

Created by: das-g

Alternative to #849

While I like this functionality being accessed through the Profile instance, I felt like the implementation was too "view-y" and not enough "model-y" to belong into the model class, so I've made the method delegate to a free function in a new module.

I'm wondering that's good or whether a model mixin would be a better idea or whether it should just be put into the model proper regardless.