don't load rspec rake tasks if on production

closes #CNVS-13742

Change-Id: Ie18a0f5198838cdfe5f680b340a4a4c0ca15b0a7
Reviewed-on: https://gerrit.instructure.com/36865
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>