'Create a new standard image and return newly-registered image-id
Note that the size of the new image is a random number between
1024 and 4096'

@classmethod
def _create_standard_image(cls, name, container_format, disk_format, size):

    image_file = six.BytesIO(data_utils.random_bytes(size))
    name = ('New    Standard    Image    %s' % name)
    image = cls.create_image(name=name, container_format=container_format, disk_format=disk_format, is_public=False, data=image_file)
    return image['id']
