add type to organisation model #25
fix urls and add query set manager #25
user admin form edit and create #25

fix form, list, remove contractors & add menu
25 - Create and edit groups + add/remove membership inside a group.
25 - Add files from previous commit
25 - List group of type department and subcontractor
remove django native user from admin
disable form when can not edit, add menu to groups #25
25 - use button to remove membership.
25 - Skin button 'Create new group'
25 - Support of can_edit
25 - Rename group list template according to user one.
25 - Add Group/User tabs
fix menu #25
upgrade south