Swamy/remove unused usings and reorganize usings (#489)

* Removed and Reordered the using statements

* Removed and Reordered the usings inside Web Project

* Removed and Reordered the usings inside PublicApi project

* Removed Unused usings and reorganized usings inside Infrastructure project

src/Web/ViewModels/File/FileViewModel.cs

@@ -1,9 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
-
-namespace Microsoft.eShopWeb.Web.ViewModels.File
+namespace Microsoft.eShopWeb.Web.ViewModels.File
 {
     public class FileViewModel
     {