Deprecated the implementation of getListPrice() and setListPrice() on SkuImpl. The Sku interface had these marked as @Deprecated already.

(cherry picked from commit bb5f8315a30320ddd6a00f183fcc96740af7ca13)
Added getPrice() to Sku/SkuImpl to resolve Sku price, considering the sale and retail prices on the Sku.

(cherry picked from commit 04b5c74a60335c4ae8d096be0c0afaee0626ad85)