packaging: setup: detect display port at runtime

previously the tool wrongly assumed that the SPICE and
the VNC port was always 5900.
It may happen however that secureDisplayPort is set to 5901
instead of 5900.
Now displayPort and secureDisplayPort are detected at runtime
querying the status of the VM.
Firewall ports 5900 and 5901 are now both open.

Change-Id: I8ae46b061b2a3ad0190f798cb141a41431120839
Signed-off-by: Sandro Bonazzola <sbonazzo@redhat.com>