Fix broken maintenance mode
Maintenance mode has been broken since r7fe19ebfe0d3 (Thu Jun 4)
"Display caught errors on the page itself", fix it by passing the
site entity, rather than the site module to isActivePeriod.
# Directions for web crawlers.
# See http://www.robotstxt.org/wc/norobots.html.
User-agent: HTTrack
User-agent: puf
User-agent: MSIECrawler
User-agent: Nutch
Disallow: /