title: Add option to form element in the controller
body: <p>Related to <a href="https://stackoverflow.com/q/14142488/1331671">this post</a> I want to transform a manual adding of a form element to <code>Annotations</code> in my <code>Entity</code>.</p>
  
  <p>The code looks like this:</p>
  
  <pre><code>$this-&gt;add(array(
      'name'       =&gt; 'formElementName',
      'type'       =&gt; 'DoctrineModule\Form\Element\ObjectSelect',
      'attributes' =&gt; array(
          'required' =&gt; true
      ),
      'options'    =&gt; array(
          'label'           =&gt; 'formElementLabel',
          'empty_option'    =&gt; '--- choose formElementName ---',
          'object_manager'  =&gt; $this-&gt;getEntityManager(),
          'target_class'    =&gt; 'Mynamespace\Entity\Entityname',
          'property'        =&gt; 'nameOfEntityPropertyAsSelect'
      )
  ));
  </code></pre>
  
  <p>As an annotation I have the problem that the <code>object_manager</code> is a variable which I cannot pass to annotations. Every other attribute is no problem and should work when being annotated.</p>
  
  <p>I'm looking for the correct way to do this:</p>
  
  <pre><code>$form-&gt;get('formElementName').setOptions(array('object_manager'=&gt;$entityManager)
  </code></pre>
  
  <p>Any ideas?</p>