Discount for Node Type Product Kit not working when used as a Product

While attempting to use this module with product kits, I found that nothing I did allowed the discount to take effect. After inspecting the code, I noticed that the code did not handle the node type of product-kit any different than product. I have written in checks for my use cases to load the product kit node, and check the products against the conditions of the discount.

For my site and for my test cases, the uc_discounts module now works correctly for products and product-kits.

I have not thoroughly tested it for all cases, so please check it over.