fix running specs in rails 3 without development gems

Change-Id: I1b659ab2f30afc460a65ad3c8851f472d2feba24
Reviewed-on: https://gerrit.instructure.com/30091
Reviewed-by: James Williams  <jamesw@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>