Fixed a bug in average when no votes are present.
Fixed a bug in average when no votes are present.

atheiste/django-generic-ratings,gradel/django-generic-ratings,fedosov/django-generic-ratings,fedosov/django-generic-ratings,atheiste/django-generic-ratings,fedosov/django-generic-ratings,gradel/django-generic-ratings,gradel/django-generic-ratings,atheiste/django-generic-ratings