Couple UI Fixes (#255)

- Disabled UI navigation cache for all pages.
- Restore the renderer<>composer page animation back.
- IdlePage functionality into mail list page.
- Couple bugfixes.

Wino.Mail/App.xaml.cs

@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
-using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AppCenter;
 using Microsoft.AppCenter.Analytics;
@@ -12,9 +11,7 @@ using Serilog;
 using Windows.ApplicationModel;
 using Windows.ApplicationModel.Activation;
 using Windows.ApplicationModel.Core;
-using Windows.ApplicationModel.Resources;
 using Windows.Foundation.Metadata;
-using Windows.Globalization;
 using Windows.Storage;
 using Windows.System.Profile;
 using Windows.UI;