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

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