Moved application code to the Application layer

Imported Win10 project
Code cleanup
WIP - Use common UWP services for Win8.1 and Win10

ModernKeePass10/ViewModels/ListItems/MainMenuItemViewModel.cs

@@ -0,0 +1,10 @@
+using Windows.UI.Xaml.Controls;
+
+namespace ModernKeePass.ViewModels.ListItems
+{
+    public class MainMenuItemViewModel: ListMenuItemViewModel
+    {
+        public object Parameter { get; set; }
+        public Frame Destination { get; set; }
+    }
+}