Creates a new subnet

def create_subnet(self, network, cidr, name=None, ip_version=4):
        '''
        Creates a new subnet
        '''
        net_id = self._find_network_id(network)
        body = {'cidr': cidr,
                'ip_version': ip_version,
                'network_id': net_id,
                'name': name}
        return self.network_conn.create_subnet(body={'subnet': body})