modules/admin-full: make mac addresses optional in static lease configuration

git-svn-id: http://svn.luci.subsignal.org/luci/trunk@9575 ab181a69-ba2e-0410-a84d-ff88ab4c47bc
po: sync base translations

git-svn-id: http://svn.luci.subsignal.org/luci/trunk@9576 ab181a69-ba2e-0410-a84d-ff88ab4c47bc