add integration type to context external tools

Fixes RD-78

Test Plan:
 - specs pass

Change-Id: I4a53cdd71784ce9e2988cbfe9b6df7e7347a9d25
Reviewed-on: https://gerrit.instructure.com/34501
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Brad Humphrey <brad@instructure.com>
Product-Review: Jon Willesen <jonw@instructure.com>
QA-Review: Jon Willesen <jonw@instructure.com>