Fix windows != to windows error on Windows2008

Resolves PE 3.2.3 and Facter 1.7.5 on Windows 2008R2 error:

```
==> default: Error: /Stage[main]/Main/Reboot[after]: Failed to call
refresh: Unsupported OS windows for Windows Provider
==> default:
==> default: Error: /Stage[main]/Main/Reboot[after]: Unsupported OS
windows for Windows Provider
```
We are already restricting to Windows above, I don't see any reason why we need to be explicit (and incorrect apparently as @nanliu has pointed out).

Thoughts @cyberious @joshcooper ??