title: Bootstrap collapsible is not hidden by default
body: <p>Ok, every single example I see online and here assumes that if you have an item marked "collapsible", then it is collapsed.  But mine is not, and I have no idea why.</p>
  
  <p>Here is my code, no different than any other example.  Yet in my app that text and button show up.  The toggling works fine.  It's the initial state which causes trouble.</p>
  
  <p>I am using Datatables - would that cause a problem?</p>
  
  <pre><code>&lt;div class="accordion-heading"&gt;
      &lt;button id="open_search" class="btn-default" data-toggle="collapse" data-target="#search_screen"&gt;
          &lt;span class="glyphicon glyphicon-filter"&gt;&lt;/span&gt;
      &lt;/button&gt;
  &lt;/div&gt;
  &lt;div  id="search_screen" class="accordion-body collapse"&gt;
      &lt;div class="accordion-toggle"&gt;testing&lt;/div&gt;
      &lt;button &gt;Hi&lt;/button&gt;
  &lt;/div&gt;
  </code></pre>