(#7621) - Added operatingsystemrelease support to Windows

Without this patch, the fact 'operatingsystemrelease' was set to kernel version fact for all the windows flavors. This patchs brings the option of having the common release name for the windows machines, something that can help in writing specific puppet manifests and other tasks according to the specific windows version.

The patch is based on a WMI call to Win32_OperatingSystem. This aproach has some drawbacks but I think the code is simple and easy to mantain and update. Anyway, extracting the windows version is not an easy task for Microsoft as well: http://msdn.microsoft.com/en-us/library/windows/desktop/ms724429%28v=vs.85%29.aspx