Fixed issue #08399: Admin can't edit another admin created user rights
Dev: removing the die and put some FlashMessage
Dev: Need decision for the rigth of each user
Dev: When deleting a user : search for 1st user without parent : this one can not be the initial super admin (good chance, but not sure)
Dev: any superadmin can update another superadmin (except initial ?)
Dev: Any superadmin can set super admin to another user (in 2.0 : only initial super admin can do it)