Add sample intro.js demo and intro banner
Remove intro_disabled helper
Add a dialog tour
Merge branch 'master' into add_js_tour

Conflicts:
	app/views/layouts/application.html.erb
	app/views/shared/_analytics.html.erb
Remove unused intro.js
Remove unused introjs CSS
Rename demo JS
Make sure the demo is restarted when the user clicks on start seller/buyer demo