Add tictactoe widget.

Thanks to @amanagr for a few refinements to my original
version, which was really raw.  (It's still raw.)

static/js/widgetize.js

@@ -5,6 +5,7 @@ var exports = {};
 var widgets = {};
 
 widgets.poll = voting_widget;
+widgets.tictactoe = tictactoe_widget;
 
 exports.activate = function (in_opts) {
     var widget_type = in_opts.widget_type;