Image added (#434)

* Image added

* ImageMaximumBytes

* FileController remove Authorized

* ApplicationCore.Constants.AuthorizationConstants.AUTH_KEY

* SavePicture in the interface.

* IFileSystem in Core

* WebFileSystem in Infrastructure

* PictureUri removed from UpdateCatalogItemRequest

* Modal scroll fix

src/Web/ViewModels/File/FileViewModel.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Microsoft.eShopWeb.Web.ViewModels.File
+{
+    public class FileViewModel
+    {
+        public string FileName { get; set; }
+        public string Url { get; set; }
+        public string DataBase64 { get; set; }
+    }
+}