Refactoring Services (#61)

* Refactoring ViewModels into Razor Pages models

* Cleaning up Basket viewcomponent

* Refactoring services.
Fixed bug in basket item counter.

src/WebRazorPages/Interfaces/IBasketViewModelService.cs

@@ -0,0 +1,11 @@
+using Microsoft.eShopWeb.RazorPages.ViewModels;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace Microsoft.eShopWeb.RazorPages.Interfaces
+{
+    public interface IBasketViewModelService
+    {
+        Task<BasketViewModel> GetOrCreateBasketForUser(string userName);
+    }
+}