Add REG_{SZ,DWORD,BINARY} helper funcs in Registry

Those lambda functions are used to set a value of type REG_SZ,
REG_DWORD and REG_BINARY in a registry node
Extend SysprepParam class to include a value check

Extend the SysprepParam class to support defining a custom check
function which can be used to check if the value given by a user when
updateing a sysprep parameter is valid.
Add extra virtio sysprep parameter in windows

This parameter points to a directory that hosts virtio drivers for
windows.
windows: Install viostor driver if missing

Add a dirty way to install the viostor driver in windows in order
to make them bootable. After booting we need to reinstall it in a
proper way. This works on Windows 2008R2