build arguments for command.

def _build_arguments(self):
        """
        build arguments for command.
        """
        # TODO: add tests to confirm deployments
        self._parser.add_argument(
            '-t', '--tag',
            required=False,
            type=six.text_type,
            default=None,
            help='This tag will override image tag provided in the configuration file.'
        )

        self._parser.add_argument(
            '-e', '--env',
            required=False,
            type=six.text_type,
            action='append',
            default=None,
            help='environment variables to create in the container at run time.'
        )