title: Don't get post with <button> tag via bootstrap
body: <p>I usually used input tag in my form:</p>
  
  <pre><code>&lt;input type="submit" value="submit" name="pass"&gt;
  </code></pre>
  
  <p>And I got <code>$_POST[pass]</code> after press button.</p>
  
  <p>Starting use <em>Bootstrap 3</em> example form with:</p>
  
  <pre><code>&lt;button type="submit" name="pass" class="btn btn-success"&gt;Submit&lt;/button&gt;
  </code></pre>
  
  <p>I got empty <code>$_POST</code>  </p>