mp_amazon_fps 6.x-1.0-alpha4

This is a reusability release and makes it easier for other modules to use the functionality within this one.

There's also minor fixes to the integration with Ubercart Amazon Payments.

Finally, _mp_amazon_fps_order_sellers() now provides a products object array for each seller. This lets an implementer use this information as needed. The product objects in this array also have a product_total property added. This is just price x quantity and again is for convenience for other modules using this function (which they can and should, despite it beginning with an underscore).