Fix person content type folderish behaviour

[iFlameing]

No description provided.

[reekitconcept]

In general this is good and it fixes the real issue correctly, but I'd like to ask you make two changes:

1. Add a test! There are zero tests for the Person serializer, which is exactly why #354's regression shipped unnoticed. Without one, the next person to touch this file reintroduces it. Minimal version, but instead of adding it myself please add it and test it out:

def test_person_is_folderish(self, portal):
    with api.env.adopt_roles(["Manager"]):
        person = api.content.create(
            container=portal, type="Person",
            id="jane-doe", given_name="Jane", family_name="Doe",
        )
        api.content.create(container=person, type="Image", id="portrait")
    result = getMultiAdapter((person, portal.REQUEST), ISerializeToJson)()
    assert result["is_folderish"] is True
    assert result["items_total"] == 1
    # the vocabulary enrichment must survive
    assert "locations" in result
    assert "organisational_units" in result

The last two assertions are the important ones. They pin both invariants together, so a future change can't trade one for the other.

2. Change the news entry name to 467.bugfix : when there is a ticket number we should use it so it shows in the changelog. We use the +personIsFolderish...bugfix format only when there is no ticket.

Please ask me to review the final again when you're done!

[iFlameing]

@reekitconcept i added the test and rename the changelog file.