don't double escape single quotes in rails 2 erb tags

test plan:
* edit a text field generated through erb (e.g.
 change the account name through account settings)
* use a single quote (')
* save the result
* confirm that when going to edit the field again, that
 it does not contain a double escaped quote ("&#x27;")

fixes #CNVS-11652

Change-Id: Ic643e00bbc56fe410a7a61ebdf4a57e9198b1f69
Reviewed-on: https://gerrit.instructure.com/34794
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
QA-Review: Clare Strong <clare@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>