Update debian package to use python3

As of version 208 the systemd package in debian dropped its bindings for python2 in favor of the python3 bindings which means the journal backend can't be used anymore with python2. The systemd maintainers are reluctant to add the python2 bindings back (See debian bug [#760635](https://bugs.debian.org/760635)).

This pull request adds a patch to the debian package which was created using the fail2ban-2to3 script and updates the dependencies for python3.

Unfortunately there are no python3 bindings for gamin, but I don't know who widespread its use is and there is still the pyinotify alternative.

I have been testing this on my server for about a week, and didn't notice any issues.