Price in tracking should be per unit, not entire line item

Description

We require the “price” element to be sent on following pages:

• Basket
• Checkout
• Order

The value of the “price” element should always match the price per unit. So, if 1 unit of an item costs 22.00 and user adds 2 units to the basket, the following is incorrect:
"items": [

],

It should be changed to this:
"items": [

],

At the moment, the Quicksilver implementation always sends a total value for this item, not the price per unit. This bug is replicated on basket, checkout and order tracking requests.
Solution: Change the “price” element to match the price per unit for these three page types.