Addition of a model mixin that is based on the new sqlalchemy docs of using `select()`, `insert()`, `update()`, `delete()`
Can be imported using `from flask_bigapp.orm import CrudMixin`
Models must have `__if_field__` and `__session__` in attributes to work with this mixin, here's an example:
python
from app import db
from flask_bigapp.orm import CrudMixin
class ExampleMixin(db.Model, CrudMixin):
__id_field__ = "example_mixin_id"
__session__ = db.session
example_mixin_id = db.Column(db.Integer, primary_key=True)
thing = db.Column(db.String(256), nullable=False)