'Adds a permission on a view or menu to the backend
:param permission_name:
name of the permission to add: \'can_add\',\'can_edit\' etc...
:param view_menu_name:
name of the view menu to add'

def add_permission_view_menu(self, permission_name, view_menu_name):

    vm = self.add_view_menu(view_menu_name)
    perm = self.add_permission(permission_name)
    pv = self.permissionview_model()
    (pv.view_menu, pv.permission) = (vm, perm)
    try:
        pv.save()
        log.info(c.LOGMSG_INF_SEC_ADD_PERMVIEW.format(str(pv)))
        return pv
    except Exception as e:
        log.error(c.LOGMSG_ERR_SEC_ADD_PERMVIEW.format(str(e)))
