Add 'clean_email' method to ProfileForm.

[TunedMystic]

When cleaning a ProfileForm, add a clean_email method.

The clean_email method should check that the given email is unique (aka it doesn't exist in the database).

In the clean_email method, if an email is NOT unique, then raise a ValidationError with an appropriate error message. Also display that error message in the template.

Check these docs for reference on ValidationErrors.

[TunedMystic]

@gitsomecode If you have any questions, feel free to reach out.