title: cakephp3 Class DateTime not found
body: <p>I'm trying to convert my cakephp plugin from 2.X to 3.</p>
  
  <p>I have a little problem inside my component plugin at this line:</p>
  
  <pre><code>$dStart = new DateTime($now); //$now = date('Y-m-d H:i:s');
  </code></pre>
  
  <p>return me this error:</p>
  
  <pre><code>Error: Class 'CurrencyConverter\Controller\Component\DateTime' not found 
  </code></pre>
  
  <p>Seems that it search DateTime inside my plugin directory.
  How can I solve it?</p>
  
  <p>Thanks</p>