Create the boto config to support standalone GSUtil.

    Args:
      project_id: string, the project ID to use in the config file.

def _CreateConfig(self, project_id):
    """Create the boto config to support standalone GSUtil.

    Args:
      project_id: string, the project ID to use in the config file.
    """
    project_id = project_id or self._GetNumericProjectId()

    # Our project doesn't support service accounts.
    if not project_id:
      return

    self.boto_config_header %= (
        self.boto_config_script, self.boto_config_template)
    config = config_manager.ConfigManager(
        config_file=self.boto_config_template,
        config_header=self.boto_config_header)
    boto_dir = os.path.dirname(self.boto_config_script)

    config.SetOption('GSUtil', 'default_project_id', project_id)
    config.SetOption('GSUtil', 'default_api_version', '2')
    config.SetOption('GoogleCompute', 'service_account', 'default')
    config.SetOption('Plugin', 'plugin_directory', boto_dir)
    config.WriteConfig(config_file=self.boto_config)