[backend] creates new models for defining a complete quiz.
[backend] basic quiz with questions / answers structure (models & API).
[frontend] renames Person factory to Participant.
[backend] put django-filter as a dependency for PROD.
[backend] api: enable filters.
Merge branch 'quiz_questions'

* quiz_questions:
  [backend] api: enable filters.
  [backend] put django-filter as a dependency for PROD.
  [frontend] renames Person factory to Participant.
  [backend] basic quiz with questions / answers structure (models & API).
  [backend] creates new models for defining a complete quiz.