[packagekit] The apt backend

[Richard Hughes]

Now we have a PkBackend instance that can take a lock, we can use apt
like apt-get, i.e. not reloading a cache on each invocation. This makes
writing a backend for apt much easier.

Now, the current apt backend is in need or some love; I get emailed
every couple of days from ubuntu people wanting to grab a deb and start
playing. I think we need to focus on the apt backend pretty seriously
now.

If any of you apt people need a hand, just just ask on list. There's
tons of people who are more than willing to help with explaining stuff.

Thanks,

Richard.