Add lucid compatibility

This has been working OK for me for a while on precise & lucid, and I'm firing off this pull request in case others would like it. 

There was a brief discussion on the <a href="https://groups.google.com/forum/#!searchin/ansible-devel/lucid/ansible-devel/FIZyrcb79bQ/Tw-GrINt5AoJ">mailing list</a>, and there was cautious acceptance of it.

I do not believe trusty's copy of `python-apt` changed the API again, although I don't test much there.

In some ways, I think the best solution would be to drop `python-apt`, and vendor the dpkg parsing code (it's gpl2+). The magic 'install python-apt under the hood' thing seems a little scary to me, and the validation code is more strict than I would like (See my other recent apt-related pull requests).