spec: fix application controller spec for rails 3

keep it from breaking later integration/controller specs

Change-Id: I56d28459a1c732386c5b0a07fb3d9671ea91cde8
Reviewed-on: https://gerrit.instructure.com/31400
Reviewed-by: Cody Cutrer <cody@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>