log-file /dev/stderr is broken for babeld as it eats log messages for debug log.
This commit gets rid of the option. This allows -d N to be used as babeld command
line option.

gluon-core, gluon-mesh-babel: move lua functions that generate ll-addresses from a mac into gluon-core

gluon-mesh-babel: babel-respond: stop relying on mac addresses and instead obtain ll-address from nic

Rename to respondd.c / respondd.so, gluon.mk expects these names. This way
we can remove the install code. The installed filename is changed to
gluon-mesh-babel.so, bringing it in line with out common naming scheme.