Implementing cart count

There are two more bits of functionality that we need to complete our shopping cart.

So here's a finished version of PrintBay, and you can see that when we add a cart item here, we get this badge over the shopping cart icon indicating how many items are in the cart currently.

Secondly, if look on the cart page, you'll see that we get a total value over here on the right, which we're not currently getting in the version we're developing.