title: Add data-attribute to selectize.js options
body: <p>I am using selectize.js for my project. But I have problems with data-attributes. I want to add data-attributes to the select options.
  I have default select like this:</p>
  
  <pre><code>&lt;option data-open-balance="false" selected="selected" value="1"&gt;PNP.SI.080416&lt;/option&gt;
  </code></pre>
  
  <p>But When I add selectize to this select, it becomes:</p>
  
  <pre><code>&lt;div data-value="1" data-selectable="" class="selected"&gt;PNP.SI.080416&lt;/div&gt;
  </code></pre>
  
  <p>I see that its "item object" only get value, and text. So, how can I add other data-attributes to its item object?</p>