xenserver-6.2: set NIC adapter 3 to promiscuous mode

Signed-off-by: David Scott <dave.scott@citrix.com>
cloudstack-infrastructure: set network adapter 3 to promiscuous mode

Signed-off-by: David Scott <dave.scott@citrix.com>
cloudstack-infrastructure: permanently enable IPv4 forwarding

This is needed because this VM is the gateway for all the nested
virt guests.

Signed-off-by: David Scott <dave.scott@citrix.com>