message: add prop type for is in CircleBadge
diff: @@ -25,7 +25,8 @@ CircleBadge.propTypes = {
  alt: PropTypes.string,
  bg: PropTypes.string,
  size: PropTypes.oneOf(['small', 'medium', 'large']),
  - src: PropTypes.string
  + src: PropTypes.string,
  + is: PropTypes.oneOfType([PropTypes.string, PropTypes.func])
  }
  export default withSystemProps(CircleBadge, COMMON)
  