title: Sonata Admin type_collection & cascade validation
body: <p>I am having a problem with implementing the one to many relationship in the sonata admin with the following structure.</p>
  
  <pre><code>-&gt;add('adhesions', 'sonata_type_collection', array('by_reference' =&gt; false,'required' =&gt; false), array(
      'edit' =&gt; 'inline',
      'inline' =&gt; 'table',
      'sortable'  =&gt; 'position',))
  </code></pre>
  
  <p>With this option : 'edit' => 'inline', i lost default validation defined in AdhesionAdmin like 'required' => true.</p>
  
  <p>So, is there a setting to specify somewhere ? I tried to add 'cascade_validation' => true in settings of the sonata_type_collection but it has not changed.</p>
  
  <p>Another question: can I use popup edit form with the sonata_type_collection ? ('edit' => 'standard')</p>
  
  <p>Any pointers and help is highly appreciated. Thank you</p>