Refactoring and Adding Tests (#28)

* Introducing repository and refactoring services.
Changing entities to use int keys everywhere.

* Refactoring application services to live in web project and only reference repositories, not EF contexts.

* Cleaning up implementations

* Moving logic out of CatalogController
Moving entity knowledge out of viewmodels.

* Implementing specification includes better for catalogservice

* Cleaning up and adding specification unit tests

src/ApplicationCore/Interfaces/IBasketService.cs

@@ -1,15 +0,0 @@
-using Microsoft.eShopWeb.ApplicationCore.Entities;
-using System.Threading.Tasks;
-
-namespace ApplicationCore.Interfaces
-{
-    public interface IBasketService
-    {
-        Task<Basket> GetBasket(string basketId);
-        Task<Basket> CreateBasket();
-        Task<Basket> CreateBasketForUser(string userId);
-
-        Task AddItemToBasket(Basket basket, int productId, int quantity);
-        //Task UpdateBasket(Basket basket);
-    }
-}