Move logic from models into logic layer

[zelima]

Currently we are using static methods in models for creating / getting / updated / deleting stuff from db (models). We need this to be moved into logic layer where it belongs and keep models as simple as possible

Acceptance Criteria

• [x] No logic in models
• [x] logic layer is organized and easily understandable

Tasks

• [x] move/update tests for static methods of models in the logic test part [1]
• [x] move functions from models to logic and delete stuff if appropriate [2]
• [x] update imports in code base as necessary
• [x] move database logic from logic __init__ .py into db_logic.py [1.5]
• [x] move Bitstore in separate module app/bitstore.py [1]
• [x] move tests for bitstore [1]
• [x] rename auth/models to auth/jwt and refactor [0.5]

[zelima]

FIXED