files umbenannt

src/gomazon/handler/product.go

src/gomazon/handler/rating.go

src/gomazon/handler/shopping_cart.go

src/gomazon/model/rating.go

src/gomazon/model/shopping_cart.go

src/gomazon/service/product.go

src/gomazon/service/rating.go

src/gomazon/service/shopping_cart.go