Switch to a different Bootstrap gem
Implement Xray
Hide correct answers in played questions

Fixes #52.
Fix quiz list layout breakage

Fixes #55.
Use a better fallback color for hero unit
Remove an unused style rule
Fix additional info not showing
Fix quiz delete confirmation modal

Fixes #60.
Make quiz progress bar differ from score

Ref. #59.
Don't animate progress bars in played quizzes

Ref. #59.
Remove obsolete code
Fix AJAX modals and make them consistent
Be more specific when selecting forms
Style student table columns
Tiny UI fix
Make the finish quiz button label more verbose
Fix heading hierarchy

Fixes #65.