allow metrowindow to set windowstyle none...

if you set the new property ```UseNoneWindowStyle```to ```True```you get this:

- no title bar
- no window commands
- no min, max, close
- no glow
- resize is allowed

the new property had to be, because the ```BorderlessWindowBehavior``` set the ```WindowStyle``` to ```None``` !!!

result with the main demo:

![image](https://f.cloud.github.com/assets/658431/1478531/649e1a5e-466d-11e3-8de2-68633a45c570.png)

Closes #717