title: Yii2 Nav Bar add images in menu items
body: <p>Is it possible to add images in Yii2 Bootstrap Nav Bar menu items?
  In  <a href="http://www.yiiframework.com/doc-2.0/yii-bootstrap-navbar.html" rel="noreferrer">official doc</a> I haven't found any option.</p>
  
  <p>I want to show images instead of Label text!</p>
  
  <p>Nav Bar code is.</p>
  
  <pre><code>&lt;?php
      NavBar::begin([
          'brandLabel' =&gt; 'My Company',
          'brandUrl' =&gt; Yii::$app-&gt;homeUrl,
          'options' =&gt; [
              'class' =&gt; 'navbar-inverse navbar-fixed-top',
          ],
      ]);
  
     $menuItems = [];
  
     $menuItems[] = [
              'label' =&gt; Yii::t('app','Language'),
              'items' =&gt; [
                  [
                    'label' =&gt; 'English', 
                    'url' =&gt; ['site/language','set'=&gt;'en'],
                  ],
  
                  '&lt;li class="divider"&gt;&lt;/li&gt;',
  
                  [
                    'label' =&gt; 'Danmark',
                    'url' =&gt; ['site/language','set'=&gt;'da'],
                  ],
  
                ],
        ];
  </code></pre>