title: backbone models and datepicker default date
body: <p>I want to display a default date in a html datepicker, like this:</p>
  
  <pre><code>&lt;input class="topcoat-text-input"id="birthday" type="date" name="birthday" value= "&lt;%=birthday%&gt;"/&gt;
  </code></pre>
  
  <p>where &lt;%=birthday%> shall be the birthday value in my backbone model, that i defined as this: </p>
  
  <pre><code>model = Backbone.Model.extend({
          defaults: {
              birthday: new Date(1984, 01, 01),
          }
  </code></pre>
  
  <p>I then have a view that gets the html template, injects the model as JSON and displays it. This works with everything else, but not the date.
  The datepicker can not display this data and just shows dd/mm/yyyy instead. How can i get it to show the date i set as default?</p>