[Testing] Adding metapackage xserver-xorg

Don't wanted this package, but it really seems to be needed since "xorg" is not  installable.
Personally I wouldn't take much priority on that but a lot of people install Ubuntu not by minimal install media and have xorg as dep which is blocking our install.
 * Fixes https://github.com/EMGD-Community/intel-binaries-linux/issues/31