Updated vendored Bootstrap assets to 2.2.2.
Added work path to SystemConfiguration.
Added assignment reference repositories, which contain reference tests, starter files, etc.
Switched around order of course and term in storage path and URLs.
Added basic "ls" method to repositories, to list contents safely.
Added attributes to check_outcomes.
Added helper method to generate Juggernaut script URL.
Added FAILED status to assignment_checks.
Using helper method for Juggernaut script.
Assignment repositories now pull starter files from the reference repository when created.
Numerous improvements to the code controller/views, and support for background checks against reference tests.