kvm - why just qcow2

[Marcus Sorensen]

Is there any reason why we only support qcow2 format on KVM? It seems
like it would be fairly simple to support other formats, qemu-img can
handle going from VMDK to RAW for example, and qemu-kvm can even use
VMDK, QED, and other formats. It even seems like QemuImg.java was
written with other formats in mind. It seems like it wouldn't be a lot
of work to simply let other formats come through, we might have to
change LibvirtVMDef a bit so it can make the proper XML.