delete database.yml.travis
apply bootstrap on top page.
Merge remote-tracking branch 'origin/master' into yo-add-bootstrap
Merge branch 'master' of github.com:yuchan/socio_quiz into yo-add-bootstrap
fix tag closing.
add association between user and quiz.
delete bootstrap js.

Loading bootstrap js slow page loading.
prevent crash on quiz form.

if user session expires, it can crash when accessing to user_id.