vga=none if x-vga passthrough is enabled

we need to disable virtual vga card if we passthrough a physical gpu

Signed-off-by: Alexandre Derumier <aderumier@odiso.com>
bump max hostpci to 4

user need to passthough 3 devices here
http://forum.proxmox.com/threads/19134-KVM-passtrought-PciExpress-3-card

Signed-off-by: Alexandre Derumier <aderumier@odiso.com>
bump version to 3.1-30