zds.article.factories.py : unused variable repo.

    | Q                         | R
    | ------------------------- | -------------------------------------------
    | Correction de bugs ?      | oui
    | Nouvelle Fonctionnalité ? | non
    | Tickets concernés         | -

* zds.article.models.py : shutil.rmtree(xxx, 0) :: correction "expected bool, got int instead"
* zds.article.urls.py : unused import views
* zds.article.views.py : unused repo variable
* zds.article.views.py : unused author variable
* zds.forum.models.py : ret = None code smell
* zds.forum.urls.py : unused import views
* zds.forum.views.py : redundant parenthesis
* zds.forum.views.py : usage of augmented assignment