Can't create admin user via admin UI

The default form at /admin/accounts/user/add/ requires you to enter the password in 
"[algo]$[salt]$[hexdigest]" form. There's a link to the "change password" form but that blows up with a 500 error (see #273)

Can we leverage whatever the 
/admin/auth/user/add/ form does so the user can just enter the password normally?
