Implement aspects

[s-kostyuk]

Implements a set of aspects or middlewares that will:

• [ ] control permission checking;
• [ ] perform logging;
• [ ] control DB Session lifecycle (i.e. opening and closing of transactions)

Blocked by #61

[s-kostyuk]

Separated to the three new tasks:

• 63, Implementation of Interceptor pattern with an attachable Aspects

• 64, Implement Transactional aspect

• 65, Implement Authentication aspect (in a form of context manager)