Add new option "as_id" to Pick*DynamicType

This option will make the app return a single id of the entity in data, and not the entity json.

src/Bundle/ChillMainBundle/Resources/views/Form/fields.html.twig

@@ -256,7 +256,8 @@
          data-types="{{ form.vars['types']|json_encode }}"
          data-multiple="{{ form.vars['multiple'] }}"
          data-uniqid="{{ form.vars['uniqid'] }}"
-         data-suggested="{{ form.vars['suggested']|json_encode|escape('html_attr') }}"></div>
+         data-suggested="{{ form.vars['suggested']|json_encode|escape('html_attr') }}"
+         data-as-id="{{ form.vars['as_id'] }}"></div>
 {% endblock %}
 
 {% block pick_postal_code_widget %}