rails3: remove duplicate route with useless :format

Change-Id: Ib9dd810631b3745938f332e485f6184942368596
Reviewed-on: https://gerrit.instructure.com/31289
Reviewed-by: Cody Cutrer <cody@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Cameron Matheson <cameron@instructure.com>
QA-Review: Cameron Matheson <cameron@instructure.com>