Remove another PHP warning from custom theme code.

themes/at_radar/templates/views-view-field--radar-event-search--title-field.tpl.php

@@ -11,7 +11,7 @@ $groups = array();
 $group_ids = $row->_entity_properties['og_group_ref'];
 // Think it's been loaded and cached anyway by the field handler, which
 // is probably where this should be done.
-foreach ($group_ids as $gid){
+foreach ((array) $group_ids as $gid){
   $node = entity_load_single('node', $gid);
   if ($node->type == 'group') {
     // If it's a group well put it in.