More detail: a commit that closes this ticket should include:

  *  Ability to add series pages and add articles to those series
  *  A way of “preheating” the SQLite cache with series metadata
  *  At least one function for listing articles on a series page
  *  Info in each article’s footer about its series and noun, if specified.
  *  An <code>index.html</code> that links to all existing Series