fix headers and add scope to the external apps table

fixes PLAT-588

test-plan
*headers for the external apps table should have scope defined on them

Change-Id: Id53d88ac2ac48ae375ada0206d282cbbf0ef58ba
Reviewed-on: https://gerrit.instructure.com/38865
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Brad Humphrey <brad@instructure.com>
QA-Review: Clare Strong <clare@instructure.com>
Product-Review: Nathan Mills <nathanm@instructure.com>