Enable UAC from registry for MPOS

If you've started to work on MPOS, you know that it will only run on Windows 8 and 2012 machines with UAC turned on.

So, to enable it directly in the registry, you can quickly go

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System

and set EnableLUA to 1. To disable it, just set it to 0 again.