title: Unable to set selected in symfony 2 twig file
body: <p>I have a form where the dropdown value is coming from another entity.</p>
  
  <pre><code>-&gt;add('country', 'entity', array(
                  'label' =&gt; 'Country',
                  'query_builder' =&gt; function (EntityRepository $er) {
                      return $er-&gt;createQueryBuilder('u')
                          -&gt;orderBy('u.countryName', 'ASC');
                  },
                  'empty_value' =&gt; 'Select Country',
                  'required' =&gt; true,
                  'mapped' =&gt; true,
                  'class' =&gt; 'BundleAdminBundle:KidsKulaCountry',
                  'attr' =&gt; array('class' =&gt; 'form-control sml-frm'),
                  //...
              ))
  </code></pre>
  
  <p>In the twig file i want to set selected the value at edit.</p>
  
  <pre><code>{{ form_widget(form.country, {value: Setcountry } ) }}
  </code></pre>
  
  <p>if I print </p>
  
  <blockquote>
    <p>{{Setcountry}}</p>
  </blockquote>
  
  <p>its returns result but it does not set selected.Please help me out.</p>