Adding this 'debian' subdirectory will allow users to build
binary packages using 'dpkg-buildpackage' and related tools.
Tested so far on Debian unstable and 9 as well as Ubuntu 17.04
and 17.10 on OpenSuSE Build Service.
'mmed' and the like all are a bit of a generic name. Let's prefix the
project name to ensure there will be no clashes with other programs that
also implement a 'MME daemon' or the like.