Bug#876899: apt: Log to the systemd journal

[Jeremy Bicha <jbicha@debian.org>]

Source: apt
Version: 1.5
Severity: wishlist

Ubuntu 17.10 has switched from the unmaintained gnome-system-log app
to gnome-logs by default. While gnome-system-log is a traditional log
viewer, gnome-logs only displays logs from systemd. apt was identified
as a particular part of the system that doesn't use systemd logging
and so this is a regression compared to previous Ubuntu releases.

I expect Debian will need to maintain the ability to emit traditional
logs without using systemd's journal. It makes sense to me for apt on
Ubuntu to use systemd logging by default, but I think it makes sense
on Debian too. At least on Ubuntu, it would make sense to *only* log
to the systemd journal (systemd can be configured to create
traditional logs for users that want that).

Thanks,
Jeremy Bicha