fix hashwithindifferentaccess deserialization in rails 2

fixes #CNVS-12075

Change-Id: I836be953ae927e3e575562e118634db84fb8167f
Reviewed-on: https://gerrit.instructure.com/32555
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jacob Fugal <jacob@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>
QA-Review: James Williams  <jamesw@instructure.com>