NuGet release v1.3.18257

Version 1.3.18257.3 - Released: 2018-09-14

Fixed

• Issue 25 - System.IO.File.Exists and System.IO.Directory.Exists don't behave as expected on UWP
  • Removed the System.IO.File.Exists and System.IO.Directory.Exists method calls from the UWP StorageFile and StorageFolder classes to prevent issues with accessing data due to limitation in Windows where data is usually isolated to the app storage.