This uses the new names introduced in edx-django-utils 3.8.0 (edx/edx-django-utils#59), which we're already using, as well as updating a few other locations where we incorrectly refer to New Relic custom metrics instead of custom attributes. Includes a couple of unrelated lint fixes in a file I modified.
common ------ This directory contains common code shared between LMS and CMS, such as Mako templates, CSS, and Coffescript.