Admin edit user profile page should not require email

In the admin UI for editing a user's profile, the screen shows the email field as required (it even uses AUI style formatting!), however email addresses are not required when adding users, nor are they required when a user edits their own profile.

We need to make these screens agree what's required and what's not. If we have time to make the user edit profile page also use the same AUIfied edit profile vm as the admin page uses, all the better.