Replace QuizModel by QuizGateway
What does this MR do?
All functions from QuizModel were moved to QuizGateway. All occurences of QuizModel were replaced by the use of QuizGateway. Added new DBConstants RoleType and SessionStatus for better readability.
How confident are you it won't break things if deployed?
Links to related issues
- added a test (partial)
- no unrelated changes -> did some refactorings in Settings module to fit to the new gateways
- asked someone for a code review
- joined #foodsharing-beta channel at https://slackin.yunity.org
- added an entry to CHANGELOG.md (description, merge request link, username(s))