Add carinho de compras e ordenação

Add ao carrinho e ordenar pelo preço.
Merge remote-tracking branch 'origin/teste' into teste

Conflicts:
	app/assets/images/maior_preco.png
	app/assets/images/menor_preco.png
	app/assets/stylesheets/application.css
	app/controllers/products_controller.rb
	app/views/products/index.html.erb