Fix ImproperlyConfigured for Django>=1.7

Based on dcramer/django-devserver#99
Add python 3 support

Ref dcramer/django-devserver#75
Fix SQLRealTimeModule to work in Django 1.7
Check if devserver overrides staticfiles runserver command

Ref: dcramer/django-devserver#100
Update version to 0.8.1 to support Django 1.7.