ovirt-iso-uploader: Add creation of VDSM user

Change-Id: Ibd024327e9263f3523fd39f632d694d55fc78161
Signed-off-by: Lev Veyde <lveyde@redhat.com>
Bug-Url: https://bugzilla.redhat.com/1129382
(cherry picked from commit a6e511dfef10ad8ed93e1ce44adb842580728514)