[packagekit] Changing the Package signal to include a type

[Richard Hughes]

After my talk at FOSDEM I got talking to the suse guys about other types
of package, such as deltarpm and binary patches. We don't want to treat
these any differently, but we might want to display a different icon in
the UI or have different update policy based on the update type.

In the yum and yum2 backends we also emit a signal called MetaData which
we don't actually do anything with. It would be also useful to push this
in to the Package signal so we don't have YAS (yet another signal) and
still can get feedback into the UI about what we are doing.

Therefore, I've changed the Package callback from:

Package(info, package_id, summary)

to

Package(info, type, package_id, summary)

I think I've updated all the backends and client code, but please can
you guys test this API change out to make sure I haven't broken
anything.

Richard.