Uninstall errors

Issue Summary

If uninstalling cck_address and any supporting modules at the same time (like the Canada module), there's an error when removing that supporting module if the main module is already gone.

Actually, the tables are all removed, but there aren't checks in the supporting module when it tries to remove its items from the shared tables.

Hmm, was that confusing? What I mean to say is, if the tables are gone, there's nothing for the supporting modules to do. So I need to make the uninstall functions end gracefully if the tables are gone. Will do it soon.