Feature request: enable Link-Local addresses on Ethernet

[brianbienvenu]

At present the BB3 doesn't acquire a link-local address ("Auto-IP") if connected to a private network without a DHCP server (eg, plugged directly into a computer).

Ideally, if there is no DHCP response for a given time period, the BB3 would automatically assign itself a random link-local address, as per https://en.wikipedia.org/wiki/Link-local_address

Without this function, an end user can still make the BB3 work, but they need to manually change the static IP to a valid one in the 169.254.0.0/16 range.