title: wordpress register_sidebar "class" does not work
body: <p>It seems simple and straightforward - but its not. </p>
  
  <p>I'm trying to register a class on the inner-part of the widget output. I'm using bootstrap 3, so I have to add a <code>panel-body</code> class to the inner part, whereas the entire widget itself is wrapped with a panel <code>panel-default</code> class.</p>
  
  <p>Example:</p>
  
  <pre><code>register_sidebar( 
          array( 
                  'name' =&gt; __( 'Home Page (Beside Content)' , 'symbiostock' ),
                  'id' =&gt; 'home-page-beside-content',
                  'class'         =&gt; 'panel-body',
                  'before_widget' =&gt; '&lt;div class="panel panel-default home-beside-content"&gt;&lt;aside id="%1$s" class="widget %2$s"&gt;',
                  'after_widget' =&gt; '&lt;/aside&gt;&lt;/div&gt;',
                  'before_title' =&gt; '&lt;div class="row panel-heading"&gt;&lt;h3 class="featured-posts col-md-12"&gt;',
                  'after_title' =&gt; '&lt;/h3&gt;&lt;/div&gt;', ) );
  </code></pre>
  
  <p>One would think the "class=>'something" would register a class in the inner part of the widget. But it does not show up. Here is what happens:</p>
  
  <pre><code>&lt;div class="panel panel-default home-beside-content"&gt;
     &lt;aside class="widget widget_text" id="text-8"&gt;
        &lt;div class="row panel-heading"&gt;
           &lt;h3 class="featured-posts col-md-12"&gt;This is a test&lt;/h3&gt;
        &lt;/div&gt;
        &lt;div class="textwidget"&gt;This is a test&lt;/div&gt;
     &lt;/aside&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>Whereas I am expecting:</p>
  
  <pre><code>&lt;div class="panel panel-default home-beside-content"&gt;
     &lt;aside class="widget widget_text" id="text-8"&gt;
        &lt;div class="row panel-heading"&gt;
           &lt;h3 class="featured-posts col-md-12"&gt;This is a test&lt;/h3&gt;
        &lt;/div&gt;
        &lt;div class="textwidget panel-body"&gt;This is a test&lt;/div&gt;
     &lt;/aside&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>Notice the <strong>"panel-body"</strong> addition.</p>
  
  <p>How can I fix this? The order of class nesting is important because I'm using bootstrap 3</p>
  
  <p><a href="http://getbootstrap.com/components/#panels" rel="nofollow">http://getbootstrap.com/components/#panels</a></p>