GridLife feed cache

Routes:
  /ics                 Seraphim's event calendar (refreshed hourly)
  /rss                 Seraphim's blog feed (refreshed hourly)
  /dg/shopping-events  Destination Guide shopping events (refreshed every 2 minutes)
  /dg/whats-hot-now    Destination Guide What's Hot Now (refreshed every 2 minutes)
  /dg/category/<name>  One Destination Guide category, e.g. /dg/category/beaches (refreshed hourly).
                       Names: new, editor, photospots, nature, beaches, romance_spots, gardens, castles, adventure, galleries, exhibits, theaters, museums, cafes, bars
  /gyazo?url=...       The direct picture address behind one Gyazo page link
  /preview?url=...     One page's title, preview picture and site name, as JSON
                       { url, title, image, site } (read once, kept for 7 days;
                       the picture itself is never fetched or stored)

Event data from Seraphim (seraphimsl.com) and Linden Lab's Destination Guide. This Worker only caches; every event links back to its source.