Comment 2 for bug 488762

My idea about ignoring CollectionField is BAD in all caps. We need a explicit way to tell snapshot what can be ignored. Maybe.

1. Define IDoNotSnapShot in lazr.lifecycle.snapshot.

2. Update laz.lifecycle.snapshot.Snapshot ignores any field that provides IDoNotSnapShot eg.
    if IField.providedBy(field) and not IDoNotSnapShot.providedBy(field):

3. Update the problem fields in Launchpad (eg. Person.allmembers, Product.branches, ...) by adding the interface to the instance attribute eg.
    IPublicPerson:
        allmembers = Exported(...)
        alsoProvides( allmembers, IDoNotSnapShot)