Update files (*.py): Remove import db and change it to import wooji. Replace all db namespace to wooji.db namespace.
Delete file (db.py): Move db.py file from the root directory to wooji/.
Create file (dbmodels.py): Create dbmodels.py used for collecting models.py of apps/ directories.
Update file (db.py): Remove codes related to collecting of models.py files and move creation of engines to dbmodels (just after collecting and importing all models.py of apps/.
Delete file (router.py): Remove this file since all routes will be run anyway when routes.py is imported.
Update file (__init__.py): Add db and dbmodels in the __init__ file so they can be available when wooji is imported.