edx/edx-platform — pull request #3968 by dmitchell (2014-06-03 15:50:44+00:00)
Title: Fix performance regression

Remove course_from_id
don't fetch whole course when the root will do
don't fetch even the root if the id will do

@chrisndodge @dianakhuang @sarina @nasthagiri some subset of you, please review