converts a TERP link in a module to an iframe hosted by Tutor

Currently the demo Tutor site is used and some basic styles applied to the iframe.  When we merge the TERP code and deploy it to production, we'll need to update this line to reflect the production URL.

cc @philschatz, @edwoodward, @kathi-fletcher
Perhaps make a config setting for it, so changes can happen w/ less ... ceremony?