Django Admin pages "View on site" link broken for users

[andrewbt]

Steps to reproduce:

1. visit a user admin page, like http://phillytreemap.org/_admin_/auth/user/175/
2. Click the gray "View on site" button in the top right corner (text of link will be something like http://phillytreemap.org/_admin_/r/3/175/)
3. Link redirects to something like http://phillytreemap.org/users/andrewbt/, but here one receives a 404 Django error page.

The proper page to redirect to in part 3 is http://phillytreemap.org/profiles/andrewbt/. /profiles/ instead of /users/.