Tag calendar and event in 4.6

[Toflar]

Here's the page example. Should be added on bothtl_calendar and tl_calendar_event, imho.

// Tag the response
if (System::getContainer()->has('fos_http_cache.http.symfony_response_tagger'))
{
    /** @var ResponseTagger $responseTagger */
    $responseTagger = System::getContainer()->get('fos_http_cache.http.symfony_response_tagger');
    $responseTagger->addTags(array('contao.db.tl_page.' . $objPage->id));
}

[leofeyer]

See #36.