'Download binary image data.
For a full list of available parameters, please refer to the official
API reference:
http://developer.openstack.org/api-ref/image/v2/#download-binary-image-data'

def show_image_file(self, image_id):

    url = ('images/%s/file' % image_id)
    (resp, body) = self.get(url)
    self.expected_success(200, resp.status)
    return rest_client.ResponseBodyData(resp, body)
