report_validation_results: properly handle not-found pages
    
    any time we couldn't instantiate a Page at all from the info
    in a ResTup (as opposed to instantiating a Page which doesn't
    exist in the wiki, which is a slightly different case) we'd wind
    up exploding further down because we'd try to iterate a None -
    we're setting a value in pagedict to None but later we try
    to do `for (page, resdict) in pagedict.values()`, which
    isn't going to end well. So, instead when we don't find a
    matching page, set the value to (None, None) and handle that
    appropriately in the one other place we check for a none-y
    value.