Adding API Endpoints for Catalog Items (#410)

* Adding new Endpoints

* update nuget packages

* Modifying API to work well with Swagger.

* Remove Swashbuckle.Core

src/Web/API/CatalogItemEndpoints/GetById.GetByIdCatalogItemResponse.cs

@@ -0,0 +1,13 @@
+using System;
+
+namespace Microsoft.eShopWeb.Web.API.CatalogItemEndpoints
+{
+    public class GetByIdCatalogItemResponse : BaseResponse
+    {
+        public GetByIdCatalogItemResponse(Guid correlationId) : base(correlationId)
+        {
+        }
+
+        public CatalogItemDto CatalogItem { get; set; }
+    }
+}