block/archipelago: Add support for creating images qemu-img archipelago:<volumename>[/mport=<mapperd_port>[:vport=<vlmcd_port>] [:segment=<segment_name>]] [size] Signed-off-by: Chrysostomos Nanakos <cnanakos@grnet.gr> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>