Remove repackage support to finish off with rollback

Remove repackage support to finish off with rollback

The two main classes of rollback/repackage need are
1) Gimme back the previous version, this broke XYZ on my system.
   This is better handled by downgrading to the previous version of original
   package instead of repackaged garbage. We should maintain real package
   (version) history somewhere.

2) Upgrade messed up my configuration.
   Instead of repackaging everything we could be far more intelligent
   wrt config files, stick them into real version control or at least have
   hooks to do so.

RPMCALLBACK_REPACKAGE_* and RPMTRANS_FLAG_REPACKAGE definitions left around
to avoid needlessly breaking everybodys callbacks (for now)