message: add dropshadow prop
diff: @@ -22,7 +22,7 @@ const styledLabel = styled('span')`
  line-height: ${theme.lineHeights.condensedUltra};
  color: ${colors.white};
  border-radius: 2px;
  - box-shadow: inset 0 -1px 0 rgba(27, 31, 35, 0.12);
  + ${props => props.dropshadow ? 'box-shadow: inset 0 -1px 0 rgba(27, 31, 35, 0.12)' : ''};
  &:hover {
  text-decoration: none;
  }
  @@ -35,7 +35,8 @@ styledLabel.defaultProps = {
  }
  styledLabel.propTypes = {
  - outline: PropTypes.bool
  + outline: PropTypes.bool,
  + dropshadow: PropTypes.bool
  }
  export default withSystemProps(styledLabel, ['space'])
  