WTF. Remove random instantiation of classes around db creation.

This is of no more use after the introduction of a metaclass in the previous commit.
Starting the models package.

This package appears to be required to split semantically to split all models
present in models.py, and to define new custom properties with our own custom
validation. Indeed, validation shall not be proformed with PUBLIC[0] LISTS[1]
{int_keys, bool_keys, ...} but checked inside the property itself.

[0] at least private...
[1] at least sets...

* Migrate old models.py to models/__init__.py.
* Create a new models/properties redefining a DateTime column parsing. This I hope, will be a good example for future   improvements of model properties.
* Test the new datetime field inheriting directly from models.Model (which has creation_date).
Having a line of 12312434324 chars is not funny.
Add a new json file providing a node, context, admin, notifications.

This may replace the shit going on in helpers.py, as I think mock data shall not
pollute helper function and obfuscate their code.
This commit applies this new fixture to TestStep.
Note: I am attempting not to use Model.update() anymore, as I do not trust it.
Trivial cleanup.

* Use assertEqual(a, b) instead of assertTrue(a == b)
* Remove unnecessary empty lines before file ends.