I want the ApiController.GetInventory to return ApiController.Models.InventoryCountApiResult.
I want to prepare for dependency injection so I can control the implementation of the Service at runtime (no need to actually try to setup any real DI framework - just get ready)
I want the ServiceLayer.InventoryService.GetCount to call StoreResponse with the response from the ApiController. I don't want the ServiceLayer to "know" about the Model (InventoryCountApiResult).