improve the model/data migration mechanism
see flyway, alembic, south, django.migrations, peewee
https://alembic.sqlalchemy.org/
https://docs.djangoproject.com/en/2.2/topics/migrations/
http://docs.peewee-orm.com/en/latest/peewee/playhouse.html#schema-migrations
original ticket : https://www.cubicweb.org/ticket/17256809