fix time_spec for rails 3

Change-Id: I11f26703b4173e6d1ccdf2ef694e781fa7adde70
Reviewed-on: https://gerrit.instructure.com/29695
Reviewed-by: Jon Willesen <jonw@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>