Clean up haml
Convert repetitions page to haml
Further convert erb to haml
Minor improvements in flashcards index view
Revert application layout to ERB (unidentified issue in flashcards index rendering)
Application layout quick fix
Convert index page template to haml
Refactor user stats template
Refactor signup page template
Refactor user settings template
Fix flashcards controller spec
Login form structure quick fix
Convert flashcard forms to haml
Restore application.html.haml (incorrect indenting only in dev environment)
Convert 'about' pages to haml