Migrations shouldn't fail RuboCop checks - especially lint checks, such
as the nested method check. To avoid changing code in existing
migrations, add the magic comment to the top of each of them to skip
that file.
Now when you want to signup or change existing email you will be forced
to confirm that you really own this email. You get email with link to
follow in order to confirm your email address
Conflicts:
app/models/user.rb