message: CHANGELOG.md: Add "Fixed" line for issue
diff: @@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
  and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
  ## [NEXT]
  +### Fixed
  +- Fixed wasteful course data usage #654 via specialized course model interfaces.
  ## [0.6.0] - 2018-03-31 - Introduces MediaManager and some minor changes
  