Fix articles key creation comment and location.

Now that I understand what the real problem is.
Fix typo in docstring.
Make the key setting in syndicalist.py work.
Add command to delete feeds.
Yes, of course we should be using PATH_INFO.
Handle notfound in 'app' via raise.

Begin simplifying code by moving one block of common error handling into
a subfunctions.
Also handle redirection via an exception.

This change also adds SCRIPT_NAME, so that the application is
now independent of its location within an ap tree, for whatever
that is worth.  Or, rather, it will be after I convert the
other redirects.
Add feed title to 'logging' of feed update.

I really ought to make that true logging.
Convert refresh_all to use Redirect.
Convert _change_article_read to use new exceptions.
Factor out parsing of feedid/articleid.

Also move grabbing arg info out of environ into the arg parsing
routine.  Because of the design of my dispatcher, the args are
*always* at the end.  (I break RESTFul conventions, but they are,
after all, only conventions.)
Refactor article to use _get_article_from_args.
Refactor _article_nav to use _get_article_from_args.

Eventually I want to change nav so that it can (optionally)
respect the 'read' flag, but that's for later.  This refactoring
makes the logic clearer and will aid making that change.