Use "< root folder >" instead of the raw project folder name in breadcrumbs

Conflicts:
	pootle/templates/translation_projects/overview.html
Use expand/collapse icons instead of text

Conflicts:
	pootle/static/css/sprite.css
	pootle/static/images/sprite.png
	pootle/static/js/stats.js
	pootle/templates/translation_projects/overview.html