title: jQuery only tick 2 checkboxes in group of 4 checkboxes
body: <p>How can I achieve in jQuery where the user can only select up to 2 checkboxes from group of 4 checkboxes? the user can select any as long as it is limited to 2 checkboxes</p>
  
  <p>this is my code</p>
  
  <pre><code>&lt;http://jsfiddle.net/4xcbye6z/&gt;
  </code></pre>