refs CNVS-4887
This probably should have happened anyway, but the intermediate model
will be necessary to handle attachments for the downloadable
quiz_statistics.csv
Test plan:
* make sure the quiz statistics page still works
* make sure downloading quiz statistics csv still works
Change-Id: I9562a731d171dae24329fc52782a4f9efa4cf8bd
Reviewed-on: https://gerrit.instructure.com/18977
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Myller de Araujo <myller@instructure.com>
Reviewed-by: Simon Williams <simon@instructure.com>
Product-Review: Simon Williams <simon@instructure.com>
Cameron Matheson