Add created and last_modified to json

Helps us write tools to find out if a package hasn't been checked off
since todolist creation.
Signed-off-by: Morten Linderud <morten@linderud.pw>

todolists/views.py

@@ -239,6 +239,8 @@ def default(self, obj):
                 'id': obj.pk,
                 'name': obj.name,
                 'description': obj.description,
+                'created': obj.created,
+                'last_modified': obj.last_modified,
                 'packages': [pkg.pkg for pkg in obj.packages()],
             }