ticket:10 signal processor (tests pass)
Merge branch 't10_signal' of
ssh://github.com/kwist-sgr/django-hello-world into t10_signal

Conflicts:
	django_hello_world/hello/management/commands/print_all_models.py
	django_hello_world/hello/migrations/0005_auto__add_modelaction.py
	django_hello_world/hello/models.py
	django_hello_world/hello/testing/__init__.py
	django_hello_world/hello/tests.py