ovirt-image-uploader: Add creation of VDSM user

Change-Id: I58506d1a979201d2026c890a8ebbb9580827d50f
Signed-off-by: Lev Veyde <lveyde@redhat.com>
Bug-Url: https://bugzilla.redhat.com/1111229
(cherry picked from commit 53631137640a9ad53c8f4e6ea9c3df240dfa3e21)