More stuff
A few more tweaks
Finally got session login working properly

I keep running into the same problem with Mongoose: I'm following an old
tutorial that has callbacks like

    function(user) {
      // do stuff...
    }

which of course fails when it should succeed, because the correct
callback form is the node.js standard

    function(err, user) {
      // do stuff...
    }

On success, `null` is passed as the first argument. Oops.