Create an ajax response framework that inserts <meta> tags to guard

against UTF-7, and create a $.gallery_autocomplete variant of jQuery's
autocomplete that expects the first line to be a <meta> tag and
discards it.  More complete fix for #1871.

modules/g2_import/controllers/admin_g2_import.php

@@ -113,7 +113,7 @@ class Admin_g2_import_Controller extends Admin_Controller {
       }
     }
 
-    print implode("\n", $directories);
+    ajax::response(implode("\n", $directories));
   }
 
   private function _get_import_form() {