fix rendering of multiple dropdowns question in rails 3

refs CNVS-13790

test plan:
 * create a quiz with a multiple drop downs question
 * preview it
 * it should render correctly

Change-Id: I8a37e0e7b8eee545252343927f8697b659726de0
Reviewed-on: https://gerrit.instructure.com/37193
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Ahmad Amireh <ahmad@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Product-Review: Brian Palmer <brianp@instructure.com>