Revise dev-server.

 * Can now issue redirections as directed by pelican/redir.cfg.
 * Properly returns 404 Not Found instead of a protocol error for
   pages that don't exist.
Disable citations, which are screwing up links in one of the old
articles.

This involved hacking up the pandoc reader, and that in turn meant
that we no longer need lib/pypandoc.py anymore, and there was much
rejoicing.