[FIX] unlink of ir.models

Some cleaning of database creation: ensure records created by
the orm (like module categories) have all an xml id.

On ir.model, store the table name. This allow deletion of models that are not in the registry anymore.


Note commit dates are in 2013 because this branch is a manual recreation of the bzr branch https://code.launchpad.net/~openerp-dev/openobject-server/trunk-fix-unlink-irmodelfields-chs