Added Python athinfod

Added athinfod.py to replace athinfod.c and related infrastructure
Added support for loading *.defs files from
/etc/athena/athinfo.defs.d.
Rename script; add setup.py

- Rename athinfod.py to athinfod, since both distutils and dh are
  incapable of renaming files while installing them, even in 2014.
- Add a setup.py for the aforementioned distutils
Update packaging for Python version

- Switch to dh7 from CDBS
- Install the Python script in /sbin
- Add a .manpages, since distutils _still_ can't deal with manpages
- Change build-deps to include python2 and debhelper with override
  target support
- Remove leading article from Description because Lintian pedantry
Remove Debian packaging from master
Retain Debian packaging on debian branch
Make the package work with git buildpackage

Add gbp.conf and source/format.