7.x metro 92

So the code here does work but this is a more "Drupal-y" way of doing this.

```php  
$tab['metadata'] = array();
  // Add Thumbnail to Object Description Tab.
  if (isset($object['TN']) && islandora_datastream_access(ISLANDORA_VIEW_OBJECTS, $object['TN'])) {
    $tab['#attached']['css'] = array(
      drupal_get_path('module', 'metrodora') . '/css/metrodora.objectdescription.css',
    );
    $image = array(
      '#prefix' => '<div class="islandora-object-description-thumbnail">',
      '#suffix' => '</div>',
      '#theme' => 'image',
      '#path' => url("islandora/object/{$object->id}/datastream/TN/view"),
      '#attributes' => array(
        'title' => $object->label,
      ),
    );
    $tab['metadata']['image'] = $image;
  }
  $tab['metadata']['markup'] = array(
    '#markup' => islandora_retrieve_metadata_markup($metadata_object, TRUE),
  );
  return $tab;
```