wip: use xvfb
Revert "wip: use xvfb"

This reverts commit 36f0b921b902803d4f19b1655b411ed92d0f3585.
Revert "Revert "wip: use xvfb""

This reverts commit 2830680bce7506b901a760467b806217c0bac9d9.
Use xvfb -> no need for X server anymore