'Extends standard admin model urls with the following:
- ``.../permissions/`` under ``app_mdodel_permissions`` url name (params: object_pk)
- ``.../permissions/user-manage/<user_id>/`` under ``app_model_permissions_manage_user`` url name (params: object_pk, user_pk)
- ``.../permissions/group-manage/<group_id>/`` under ``app_model_permissions_manage_group`` url name (params: object_pk, group_pk)
.. note::
``...`` above are standard, instance detail url (i.e.
``/admin/flatpages/1/``)'

def get_urls(self):

    urls = super(GuardedModelAdminMixin, self).get_urls()
    if self.include_object_permissions_urls:
        info = (self.model._meta.app_label, get_model_name(self.model))
        myurls = [url(u'^(?P<object_pk>.+)/permissions/$', view=self.admin_site.admin_view(self.obj_perms_manage_view), name=(u'%s_%s_permissions' % info)), url(u'^(?P<object_pk>.+)/permissions/user-manage/(?P<user_id>\\-?\\d+)/$', view=self.admin_site.admin_view(self.obj_perms_manage_user_view), name=(u'%s_%s_permissions_manage_user' % info)), url(u'^(?P<object_pk>.+)/permissions/group-manage/(?P<group_id>\\-?\\d+)/$', view=self.admin_site.admin_view(self.obj_perms_manage_group_view), name=(u'%s_%s_permissions_manage_group' % info))]
        urls = (myurls + urls)
    return urls
