Replace HomeSettings with Presence Model class. Replace SiteSettings with
Site Model class. Derive Group Model class from Presence, adding the "home
page settings" properties in a Melange site presence to every Group.
Patch by: Todd Larsen
# 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: /