Attach network to VPN gateway
        :Param  req
        :Type   object Request

def attach_vpngw(self, req, id, driver):
        """Attach network to VPN gateway
        :Param  req
        :Type   object Request
        """
        vpngw = driver.get_vnpgw(req.params, id)
        if vpngw is None:
            vpngw = driver.create_vpngw(req.params, id)
        response = driver.attach_vpngw(req.params, vpngw)
        data = {
            'action': 'attach_igw',
            'controller': 'network',
            'id': id,
            'cloud': req.environ['calplus.cloud'],
            'response': response
        }
        return data