frd fix student_reports_spec for rails 3

Change-Id: I480f8e6a31ee36a78c67dcea653d778accf4d921
Reviewed-on: https://gerrit.instructure.com/31140
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>
QA-Review: James Williams  <jamesw@instructure.com>