6relayd: more verbosity in leases and logging

git-svn-id: svn://svn.openwrt.org/openwrt@36764 3c298f89-4303-0410-b956-a3cf2f4a3e73
AA: 6relayd: backport r36764

git-svn-id: svn://svn.openwrt.org/openwrt@36765 3c298f89-4303-0410-b956-a3cf2f4a3e73