title: Cakephp 3 Formhelper input : how to add a css class attribute
body: <p>I'm trying to add a css class attribute to a field but i have a small problem :</p>
  
  <pre><code>echo $this-&gt;Form-&gt;input('dateLimite', ['type'=&gt;'text', 'foo' =&gt; 'bar', 'class' =&gt; 'datepicker']);
  </code></pre>
  
  <p>Output :</p>
  
  <pre><code>&lt;input class="form-control" type="text" name="dateLimite" foo="bar" required="required" id="datelimite"&gt;
  </code></pre>
  
  <p>The class attribut cannot be displayed. Have you an idea please ?</p>