fix courses controller for rails 3 specs

Change-Id: I2f24f493f616970f9d613bda5225d2a08b530949
Reviewed-on: https://gerrit.instructure.com/29875
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>