Add "Created on" in Review model

[VladaAlek]

User Story

As a user I can see the automatically generated date when my post was created so that I can monitor the temporal component of my activities.

Acceptance Criteria

• [x] AC 1 "Created on" is generated and visible in the Review page
• [ ] AC 2
• [ ] AC 3
• [ ] AC 4

Tasks

• [x] T1 change the Review model
• [x] T2 migrate
• [x] T3 test the functionality
• [ ] T4