This was added in here as a shim to catch places that were still using the old version of these models that had an attribute called course_id instead of the `course` foreign key. After monitoring production for two weeks, we can be pretty confident that we've caught most places that do this. Removing this code since it should no longer be needed.
common ------ This directory contains common code shared between LMS and CMS, such as Mako templates, CSS, and Coffescript.