fix spec failures for notifications

specs fail because evidently the notification model
expects to receive the :frequency parameter

Change-Id: I7ddd9e98a1c65ccf839256b460cc96af76afc849
Reviewed-on: https://gerrit.instructure.com/28365
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Anthus Williams <awilliams@instructure.com>
QA-Review: Anthus Williams <awilliams@instructure.com>
Product-Review: Anthus Williams <awilliams@instructure.com>