### Add item to cart
POST https://cart.tornberg.me/api/12345
Content-Type: application/json

{
	"sku": "763281",
	"quantity": 1
}

### Update quanity of item in cart
PUT https://cart.tornberg.me/api/12345/1
Content-Type: application/json

{
	"quantity": 1
}

### Add item to cart
POST http://localhost:8080/cart/12345/item
Content-Type: application/json

{
	"itemId": "67890",
	"quantity": 2
}

### Remove item from cart
DELETE http://localhost:8080/cart/12345/item/67890

### Checkout cart
POST http://localhost:8080/cart/12345/checkout
Content-Type: application/json

{
	"paymentMethod": "credit_card",
	"shippingAddress": "123 Main St, Anytown, USA"
}