title: How to edit or remove title property from sort icon in angular ui-grid
body: <p>Is it possible to disable showing title when user made sort for column and then hover on arrow icon? I didn't find any variants besides to change uiGridHeaderCell.html manually.</p>
  
  <p>Is there any option to remove that title or to change it to show current sort direction?</p>
  
  <p><a href="https://i.stack.imgur.com/xQ96a.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xQ96a.png" alt="enter image description here"></a></p>