s/ActionController/ActionDispatch/

Change-Id: I4b4cab7e8cf1228e19bbdc4bcfe1059dc2f4265d
Reviewed-on: https://gerrit.instructure.com/41627
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: James Williams  <jamesw@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>