fix collection proxy respond_to for rails 3

Change-Id: Ife5a250838daf399b00e8d24f037da0998b7e2e8
Reviewed-on: https://gerrit.instructure.com/31314
Reviewed-by: Cody Cutrer <cody@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>
QA-Review: James Williams  <jamesw@instructure.com>