Increase size of first disk for slave nodes in VirtualBox

When the Ceph role is selected 16GB isn't enough to satisfy
the minimum space requirements for all volume groups.

Change-Id: I24d51c64b183455dceffbf8cb8813395aaf46142
Related-Bug: #1248662
Ceph build tweaks. Do not merge.

Change-Id: If7f369078f5e1b559a2ec2aa9429f3759e037ba4
Allow NAT_USE_DHCP option

Add NAT_USE_DHCP option to enable DHCP server on NAT interface for
 those that use it.

Change-Id: Iadac4a2db3e5f71df2a22327994c0b0a73572d41
Revert "remove dublication for internal_net"

This reverts commit e40a35e79b13de15ecae880160a7666b8f36c11e.