title: symfony2 tetranz select2entity-bundle
body: <p>I'm currently using select2 v4, since this now requires a select and not an input i'm having issues validating options as i'm loading these via ajax.</p>
  
  <p>I installed the tetranz/select2entity-bundle (<a href="https://github.com/tetranz/select2entity-bundle" rel="nofollow">https://github.com/tetranz/select2entity-bundle</a>). I followed the instructions thouroughly and i'm now receiving this error after install:</p>
  
  <pre><code> The option "multiple" does not exist. Known options are: "action", "attr", 
  "auto_initialize", "block_name", "by_reference", "cascade_validation", 
  "compound", "constraints", "csrf_field_name", "csrf_message", 
  "csrf_protection", "csrf_provider", "csrf_token_id", "csrf_token_manager", 
  "data", "data_class", "disabled", "empty_data", "error_bubbling", 
  "error_mapping", "extra_fields_message", "inherit_data", "intention", 
  "invalid_message", "invalid_message_parameters", "label", "label_attr", 
  "mapped", "max_length", "method", "pattern", "post_max_size_message", 
  "property_path", "read_only", "required", "translation_domain", "trim", 
  "validation_groups", "virtual"
  
  500 Internal Server Error - InvalidOptionsException 
  </code></pre>
  
  <p>Additionally to the installation my form builder ->add looks like this:</p>
  
  <pre><code>       -&gt;add('receiver_physician', 'tetranz_select2entity', array(
             'multiple' =&gt; false,
             'remote_route' =&gt; 'ajax_physician_search_by_term',
             'class' =&gt; '\HospitalBundle\Entity\Physician',
             'text_property' =&gt; 'name',
             'minimum_input_length' =&gt; 2,
             'page_limit' =&gt; 10,
             'placeholder' =&gt; 'Select a Physician',
         ))
  </code></pre>
  
  <p>Anyone else had this issue?</p>