title: printing pie's dataLabels numbers with commas
body: <p>I'm trying to print numbers with commas (showing 9,000 instand of just 9000), this is the way I'm setting the format
  <code>format: '{point.name}: {point.y}'</code></p>
  
  <p>I cant find a way to get <code>{point.y}</code> into a function that will return the wanted result, 
  I tried this way <code>format: '{point.name}: '+ numberWithCommas(point.y)</code> but then of course <code>point is not defined</code> I'm not sure how to handle it,
  any direction how can I make it work ?</p>
  
  <p>thanks</p>