Self-registration form: require either phone or email

[Jane Sandberg]

We've started using the self-registration form, using a model where we get in touch with new patrons after they submit the form.

To do this, we need either an email address or a phone number. However, we don't want to require both -- some patrons don't have an email address; others don't prefer to use a phone. It would be great if there were some validation on a form where a patron must supply at least one of these two fields.