Add attribute class which uses properties, accessors, or callables.

* Add test case.
Add adapter base class.
Add Yii test base class that manages framework loading.
Remove old Yii test classes and configuration file.
Add ActiveRecord adapter container and factory.

* Add test case.
Refactor ActiveAdapter.

* Update to match new adapter interface.
* Add relations attribute classes.
* Add new mock based test case.
* Apply PSR-2 style.
* Remove model proxy and iterator classes.
Add class to represent HTTP responses with JSON API format.

* Add test case.
Add utility class to handle JSON API HTTP requests.

* Add test case.