title: Finding out scroll direction in react-native listview/scrollview
body: <p>Is there a way to find out the scroll direction of react-native's listview/scrollview components?</p>
  
  <p>Native iOS components seem to be able to do it by calculating the offset from <code>scrollViewWillBeginDragging</code> and <code>scrollViewDidScroll</code>, but there seems to be no bindings for these.</p>