Custom permissions

[Mischback]

IOT enhance the admin panel, create custom permissions. This will enable a more flexible way of user management, because it does not rely exclusively on superusers.

• create custom permissions
  • view user list
  • activate user
  • deactivate user

Issues

• if an object/model is accessible in the admin-panel relies on the (given) can_modify-permission. Some dirty hack is required, to enable staff-users to actually view the user list.
• is_staff allows sign in into the admin panel
• can_modify is required to actually see a model
• create some custom admin view, to show the user-list to those users with custom permissions below can_modify.