docs: def image_export(self, image_name, dest_url, remote_host=None):
          """Export the image to the specified location
          :param image_name: image name that can be uniquely identify an image
          :param dest_url: the location of exported image, eg.
          file:///opt/images/export.img, now only support export to remote server
          or local server's file system
          :param remote_host: the server that the image will be export to, if
          remote_host is None, the image will be stored in the dest_path in
          local server,  the format is username@IP eg. nova@9.x.x.x
          :returns a dictionary that contains the exported image info
          {
          'image_name': the image_name that exported
          'image_path': the image_path after exported
          'os_version': the os version of the exported image
          'md5sum': the md5sum of the original image
          }
          """
          try:
              return self._imageops.image_export(image_name, dest_url,
                                                 remote_host)
          except exception.SDKBaseException:
              LOG.error("Failed to export image '%s'" % image_name)
              raise