This patch introduces a new yang yang model for DHCP server and relay,
using dnsmasq to provide the functionality on a per-interface basis.
Available DHCP options will be queried by confd on startup and can
then be configured in a flexible manner.
The DHCP option 82 feature has been realized by patching dnsmasq
(see patches/dnsmasq/2.90/0000-relay-agent-info.patch).
Signed-off-by: Stefan Schlosser <sgs@grmmbl.org>
