rails 3 doesn't auto-require csv, so require it where necessary

Change-Id: Id76980c82024a082855f5b7b5b60cd7e760730a9
Reviewed-on: https://gerrit.instructure.com/30132
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Derek DeVries <ddevries@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>