Add guard for creating admin user. Closes #810.

Makefile

@@ -67,7 +67,7 @@ server-migrate:
 	$(PYTHON) quipucords/manage.py migrate --settings quipucords.settings -v 3
 
 server-set-superuser:
-	echo "from django.contrib.auth.models import User; User.objects.create_superuser('admin', 'admin@example.com', 'pass');print(User.objects.filter(email='admin@example.com'))" | $(PYTHON) quipucords/manage.py shell --settings quipucords.settings -v 3
+	echo "from django.contrib.auth.models import User; admin_not_present = User.objects.filter(email='admin@example.com').count() == 0;User.objects.create_superuser('admin', 'admin@example.com', 'pass') if admin_not_present else print('admin present');print(User.objects.filter(email='admin@example.com'))" | $(PYTHON) quipucords/manage.py shell --settings quipucords.settings -v 3
 
 server-init: server-makemigrations server-migrate server-set-superuser