Dettach network from Internet gateway
        :Param  req
        :Type   object Request

def dettach_igw(self, req, driver):
        """Dettach network from Internet gateway
        :Param  req
        :Type   object Request
        """
        response = driver.dettach_igw(req.params)
        data = {
            'action': 'attach_igw',
            'controller': 'network',
            'id': id,
            'cloud': req.environ['calplus.cloud'],
            'response': response
        }
        return data