put migration file in the right place

Change-Id: I27b59ed4ca6e10eda62327adaadfb580648cd46e
Reviewed-on: https://gerrit.instructure.com/29949
Reviewed-by: Rob Orton <rob@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Simon Williams <simon@instructure.com>
QA-Review: Simon Williams <simon@instructure.com>