As the data is just going to an email (and not into a database or something), I'm not enforcing any particular date format here. Using `forms.DateInput` would make Django validate the format. All I really care about here is that data is entered.

This came after a bit of discussion and attempts at using a fallback JavaScript datepicker...which turns out to just be more work than it's worth. I think we can trust users to enter a decipherable date. On the off chance they don't, we have their email to contact them.