Remove optional profile questions from CMS

These will be replaced with optional modules. Automatically perform this
conversion on import.
Remove optional profile questions from client.
Framework for converting optional profiles.
Implement in-place data migration part 1
Get some test coverage going.
Update documentation for pq->module changes
Update changelog for Plone upgrade.
Sync prototype profile page with app.
Document profile-to-module merge effects.
Fix syntax error in test.