jquery 1.x and 2.x use same api
http://lists.alioth.debian.org/pipermail/pkg-javascript-devel/2015-September/011230.html

--- a/app/assets/javascripts/application.js
+++ b/app/assets/javascripts/application.js
@@ -4,7 +4,7 @@
 // It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
 // the compiled file.
 //
-/*= require jquery2 */
+/*= require jquery */
 /*= require jquery-ui/autocomplete */
 /*= require jquery-ui/datepicker */
 /*= require jquery-ui/draggable */