Creating qtenv2.bat for WinRT and enable WinRT plugin.

Change-Id: I0e28554c7a599f9519957d4644d13fc4a87e9a95
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Iikka Eklund <iikka.eklund@digia.com>
Reviewed-by: Andrew Knight <andrew.knight@digia.com>