Added SystemConfiguration resource.
Made error layouts DRYer; added error modal popups for errors during Ajax requests.
Added 'git' gem dependency.
Minor CSS fix for examples on home page.
Improved display of form errors in modal dialogs.
Put example repositories back into course offerings instead of courses; added initial views and logic for managing them.
Home controller improvements; FriendlyUrlController that home and code can inherit.
Code controller updates.
Added exception message to 404 page so admins can see the resource that was requested.
Significantly cleaned up Ability and other course-related associations.
Updated stale unit tests.
Updated schema after a recent migration.
Added access controls and tests for example repositories.
Added method to retrieve other concurrent offerings from a course offering.
Example repositories destroy linked repos when destroyed.
Added ability to create example repositories that are shared across all concurrent offerings of a course.
Made page titles customizable.
Added open method to Repository.
Began improving code view UI; added auto-saving support.
Added 'juggernaut' and 'redis' gem dependencies.