Added 'mysql2' and 'sidekiq-failures' gems; also 'codemirror-rails' gem with vendored assets, now that Codemirror 3 is out and the gem supports it.
Added EST as default time zone.
Changed default tooltip placement; added Bootstrap-style alert and confirm dialogs.
Added line info for runtime errors that don't normally come with it.
Major updates to code controller styling, assignment handling and display, and started support for checking assignments against reference tests in the background.
More code and assignment viewing improvements.
Created CheckOutcome model. A "check" is composed of many "outcomes"; an outcome is something like a test case result, or a style analysis, and these are combined to determine the student's results of that check.