Metro notifications

Introduce Metro notifications (Win 8 only).  Note that to display a metro notifications, you need to have a link installed on the start menu.  This will install an invisible link when the `debugInstall` configuration value is `true`.
Hmm.  It should be.  This is the new Windows RT API.  When you set TargetPlatformVersion=8 you should be able to take a reference on this (though you won't find this DLL on your system).  There's much magic going on here behind the scenes and I don't know all the details, but it should work in Windows 8.0 or better and VS 2013 or better.

Which VS are you running that this is failing?