fix unit tests for py3
fix unit tests for py3

GrahamDigital/django-scheduler,GrahamDigital/django-scheduler,drodger/django-scheduler,nharsch/django-scheduler,nharsch/django-scheduler,llazzaro/django-scheduler,GrahamDigital/django-scheduler,drodger/django-scheduler,sprightco/django-scheduler,sprightco/django-scheduler,drodger/django-scheduler,llazzaro/django-scheduler,sprightco/django-scheduler,llazzaro/django-scheduler