Flask-sqlalchemy-bundle

* fix required validator
* support using translations in validation error messages
* export the BaseValidator and Required classes on the extension

* fix `render_migration_item` when second argument is `None`
* add `commit` kwarg to `ModelManager.get_or_create`
* add support for validation on sqlalchemy models

* bugfix: Query.get should accept a tuple (for composite primary keys)

* add ModelManager and SessionManager service classes
* support extending the SQLAlchemy extension and specifying a custom model
* add a bunch of class Meta optional magic
* automatic primary key columns
* automatic time stamping
* improved polymorphic mapping
* improved materialized views
* add some pytest fixtures
* add a bunch of tests
* support lazy-mapped model classes
* add support for PostgreSQL materialized views
* switch from Flask-Alembic to Flask-Migrate

* initial release