fix flake error and style re formatted in models
fix flake error and style re formatted in models

pombredanne/django-activity-stream,jrsupplee/django-activity-stream,thelabnyc/django-activity-stream,pombredanne/django-activity-stream,thelabnyc/django-activity-stream,justquick/django-activity-stream,justquick/django-activity-stream,jrsupplee/django-activity-stream