feat: add claim hook that "warms up" free addresses

[mkg20001]

See #4 (comment)

Example hook to work with l3roamd

#!/bin/sh

# NOTE: we need to prefix with ::ffff: in del_address because of a bug in l3roamd
# add_address is modified for consistency

case "$1" in
	lease)
		echo add_address "::ffff:$2" "$3" | uc /var/run/l3roamd.sock
		;;

	release)
		echo del_address "::ffff:$2" "$3" | uc /var/run/l3roamd.sock
		;;


	claim)
		ip route add "$2" dev local-node proto 158
		;;

	claimrelease)
		ip route del "$2" dev local-node proto 158
		;;
esac