[packagekit] Resolve method

[Richard Hughes]

Guys,

The Resolve() method is important for pk-install-package functionality
and I consider it a blocker for 0.1.0. It should be trivial to implement
for most of the backends as it's basically a trivial search that doesn't
look at other names than the direct name, and errors out if there is
more than one match.

Yell if you need a hand, or there's lots of info in the docs.

Thanks,

Richard.