Adding unit tests, refactoring file access to a service, adding CatalogImageMissingException.

src/ApplicationCore/Interfaces/IBasketService.cs

@@ -14,5 +14,4 @@ namespace ApplicationCore.Interfaces
     {
         T Parse(IPrincipal principal);
     }
-
 }

src/ApplicationCore/Interfaces/IImageService.cs

@@ -0,0 +1,16 @@
+using ApplicationCore.Entities;
+using Microsoft.eShopWeb.ApplicationCore.Entities;
+using System.Security.Principal;
+using System.Threading.Tasks;
+
+namespace ApplicationCore.Interfaces
+{
+
+    public interface IImageService
+    {
+        byte[] GetImageBytesById(int id);
+    }
+
+
+
+}