little changes

src/homework/__init__.py

src/homework/admin.py

src/homework/apps.py

src/homework/migrations/0001_initial.py

src/homework/migrations/0002_auto_20180411_0047.py

src/homework/migrations/__init__.py

src/homework/models.py

src/homework/serializers.py

src/homework/tests.py

src/homework/urls.py

src/homework/views.py