Allow invalidated archive data to be used until they are re-processed

Added DONE_INVALIDATED flag to archiving and considering it when fetching archives
to make it easier to spot that NewDataShouldNotAppear and NewDataShouldAppear here is a suggestion: in the fixture for this "new data" make the fixture data clear, for example change the page titles to "New Page3" or the url to "/category/new-page3". This way it's easy to see the difference with and without the new data. does it make sense?