fixes in set_route for null

public/js/wn/router.js

@@ -72,7 +72,7 @@ wn.get_route_str = function(route) {
 }
 
 wn.set_route = function() {
-	route = $.map(arguments, function(a) { return encodeURIComponent(a) }).join('/');
+	route = $.map(arguments, function(a) { return a ? encodeURIComponent(a) : null; }).join('/');
 	window.location.hash = route;
 	
 	// Set favicon (app.js)