Many-to-Many and Custom ORM mappings issues

Hi guys,

I found some issues with Many-to-Many associations and Custom ORM mappings,
and created the following JIRA tickets:
- GRAILS-2922
- GRAILS-2923

Just wanted to point some attention to it on the dev list,
as this causes some unexptected behaviour in case you develop against a fixed legacy database.

Cheers,
Marcel