Adds a constraint of 500 records at a time

Example given with 5000 records cripples the filter, this cap will keep it usable until we develop a better solution.
Refs #3202

modules/backend/widgets/Filter.php

@@ -370,8 +370,15 @@ class Filter extends WidgetBase
     protected function getOptionsFromModel($scope, $searchQuery = null)
     {
         $model = $this->scopeModels[$scope->scopeName];
+
         $query = $model->newQuery();
 
+        /*
+         * The 'group' scope has trouble supporting more than 500 records at a time
+         * @todo Introduce a more advanced version with robust list support.
+         */
+        $query->limit(500);
+
         /*
          * Extensibility
          */