UEC install from CD automatically selects DHCP if available

[Mark Russell]

Binary package hint: debian-installer

- 10.04 LTS Server install media.
- Select "Install Ubuntu Enterprise Cloud" from menu.
- If there is a DHCP server on the same LAN segment (broadcast domain) as the new UEC install, d-i will autoconfigure DHCP for the target server.
- Adding "netcfg/disable_dhcp = true" should perhaps be added to the cloud.seed to prevent this. It's not trivial to undo this after the install with UEC servers.

Note: can be worked around by simply pulling the cable before d-i looks for a network connection and plugging it back in when you are offered the chance to configure IP manually.