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/ApplicationCore/Interfaces/IFileSystem.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace Microsoft.eShopWeb.ApplicationCore.Interfaces
+{
+    public interface IFileSystem
+    {
+        Task<bool> SavePicture(string pictureName, string pictureBase64);
+    }
+}