WIP: Multiple catalog

This work is on top of erp5_catalog branch, so we are using erp5 catalog everywhere in this case.

Multiple Catalog:

1. Site Manager creates multiple catalog using different connections.
2. Each erp5_catalog comes with a predicate object.
3. Extra attributes for catalog objects:
   • Validation state : Cataloging would be done only in validated catalogs.
   • Predicate: Predicate would be checked on each object to be cataloged.
4. Every user would have preference to chose the preferred_catalog and that one would be used as the result of getSQLCatalog, without changing default_erp5_catalog_id

Problems:

• Circular dependency while looking for preferred_catalog. For now, this has been taken care of by using default_erp5_catalog_id for the result of getSQLCatalog in case the user is manager. So, this way atleast we have all user and preferences cataloged at one place.