Added 2 methods to get and create images for a specific product.
The problem is the naming of the method "get_product_images" and "create_product_images" aren't quite right because all product resources are named plural. But I don't really know how to name them.
This should be added for every product specific resource like videos or discount rules.
add get_product_images and create_product_images method
Those methods are named correctly—it should be plural for a collection resource (ie: /products), and singular for an entity resource (ie: /products/1).