title: Do not display several Glyphicons icons
body: <p>Rails 4, Bootstrap 3
  Do not display complicated  Glyphicons icons</p>
  
  <p>displayed(this and other elementary): </p>
  
  <pre><code>&lt;i class="glyphicon glyphicon-minus"&gt;&lt;/i&gt;
  </code></pre>
  
  <p>not displayed(This and all which need complex rendering): </p>
  
  <pre><code> &lt;i class="glyphicon glyphicon-earphone"&gt;&lt;/i&gt;
  </code></pre>
  
  <p>With what it can be connected?</p>