fix ember quizzes tests by making responses fresh on each setup

Temporary fix until we merge in a commit from ic-ajax that does this
automatically.

Change-Id: Iebaa987354eba4fa5796af50ea94f115dfd1f8f2
Reviewed-on: https://gerrit.instructure.com/31898
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jacob Fugal <jacob@instructure.com>
Product-Review: Stanley Stuart <stanley@instructure.com>
QA-Review: Stanley Stuart <stanley@instructure.com>