Convert object to match valid docker-py properties.

def docker_py_dict(self):
        """Convert object to match valid docker-py properties.
        """
        return {
            'image': self.image,
            'command': self.cmd,
            'hostname': self.hostname,
            'user': self.user,
            'detach': self.detach,
            'stdin_open': self.open_stdin,
            'tty': self.tty,
            'ports': self.exposed_ports,
            'environment': self.env,
            'volumes': self.volumes,
            'network_disabled': self.network_disabled,
            'entrypoint': self.entry_point,
            'working_dir': self.working_dir,
            'domainname': self.domain_name,
            'labels': self.labels
        }