devilry_gradingsystem: Groundwork for markdown editor widget.
devilry_gradingsystem: Pulled ace-builds from bower.
devilry_gradingsystem: Usable ACE editor.
devilry_gradingsystem: Style the editor.
apps.markup.parse_markdown: Update markdown config to be much closer to

GitHub and Stackoverflow.
devilry_examiner: Added pygments CSS.
devilry_gradingsystem.views.feedbackeditorbase: Convert feedbacktext to markdown.