Fix regression for django.db.transaction.managed
Use celery.app package instead of deprecated celery.task.
Heads up that task.delay() returns None, not AsyncResult.
Merge branch 'asyncresult-not-returned' of https://github.com/fladi/django-celery-transactions
Merge branch 'fix-regression' of https://github.com/ticosax/django-celery-transactions
Merge branch 'celery-3.x' of https://github.com/fladi/django-celery-transactions