Revert "Revert "Avoid creating /nonexistent on compute nodes too""

This reverts commit 22374896c6d797a50f956935aa86779387deca90.
Revert "Revert "Create system users for OpenStack components""

This reverts commit f85347c31cfe456bbe5c2187ea01da0f1757f78e.
System users for new deployments
changed_when: False
Merge pull request #207 from blueboxgroup/system-users-again

System users again