move js/css files into respective directories, add some redirects to app/ directory, move feedback.html into app/send_feedback.html

--HG--
rename : feedback.html => app/send_feedback.html
rename : safe_button.css => css/safe_button.css
rename : feedback.js => js/feedback.js
rename : flexfooter.js => js/flexfooter.js
rename : jquery.js => js/jquery.js