Order JSON contains duplicate product information in manifest

[radar]

Check out this response: https://gist.github.com/radar/9797853

In the manifest for the shipment, I can see the variant information being returned. This exact same information is returned in the line items response. I don't see any particular reason to have this huge block of information repeated here, and so we should restrict it to probably just the line item's id.

[radar]

I've got a fix for this on my master branch. It shouldn't be applied to 2-2-stable because it will break
backwards compatibility.