do some minor datafixups before adding schema constraints

Change-Id: Ic4e887b46a8035daafb0bc0491ead1f0fc52557c
Reviewed-on: https://gerrit.instructure.com/29402
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Rob Orton <rob@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>