fix assessment_question_spec for rails 3

Change-Id: Id119b2cb63150c998689adf9d92eca5f195847a8
Reviewed-on: https://gerrit.instructure.com/28689
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>