Related hasMany versioning

[TeckniX]

It seems that by default cake does not load behaviors for related models, which makes creating versioning of a related model that is not HABTM difficult.

It seems that following some of the HABTM logic, one could do the same loop to serialize the hasMany arrays and save them in the shadow table.
1 field per relationship and the behavior could be updated to expect those.

Is this valid, or non-relevant, as there is a better way of doing it? I'll be more than happy to fork the file and prompt for a pull request with my changes.