#4205 (ok 4.1.3) Add a user shows additional "edit user group" link

[J.M. Rütter]

When there are no user groups defined, the "Edit user group" link is hidden for all existing users in the "User privileges" view (server mode). When a new user is added, though, the link is displayed nevertheless. The link should be hidden for new users, too, as long as there are 0 user groups defined.