title: How to add 'id' to a widget in GridStack
body: <p>I would like to use Gridstack for my project and I am playing with it, right now I am adding widgets with JSON data. I am not able to add an id to the widget. </p>
  
  <p>Here is a link to <a href="https://jsfiddle.net/Kami924/4c0L5s0w/12/" rel="nofollow">JsFiddle</a>. This 'id' is very important because without it I wont be able to save/retrieve data from DB.</p>
  
  <p>According to <a href="https://github.com/troolee/gridstack.js/issues/188" rel="nofollow">this post</a> on guthub, I am providing the id to ** <code>grid.add_widget</code>** method. But I don't know how I can access it. </p>