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/IAppLogger.cs

@@ -1,5 +1,9 @@
 namespace ApplicationCore.Interfaces
 {
+    /// <summary>
+    /// This type eliminates the need to depend directly on the ASP.NET Core logging types.
+    /// </summary>
+    /// <typeparam name="T"></typeparam>
     public interface IAppLogger<T>
     {
         void LogWarning(string message, params object[] args);