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/Exceptions/CatalogImageMissingException.cs

@@ -2,6 +2,9 @@
 
 namespace ApplicationCore.Exceptions
 {
+    /// <summary>
+    /// Note: No longer required.
+    /// </summary>
     public class CatalogImageMissingException : Exception
     {
         public CatalogImageMissingException(string message,
@@ -14,5 +17,13 @@ namespace ApplicationCore.Exceptions
                   innerException: innerException)
         {
         }
+
+        public CatalogImageMissingException() : base()
+        {
+        }
+
+        public CatalogImageMissingException(string message) : base(message)
+        {
+        }
     }
 }