fix(server): fix configuration so that (express) errorHandler works

The error handler needs to be below app.use(app.router), otherwise it's never used.

templates/express/config/express.js

@@ -60,7 +60,12 @@ module.exports = function(app) {
     app.use(passport.initialize());
     app.use(passport.session());
     <% } %>
-    // Router needs to be last
+    // Router (only error handlers should come after this)
     app.use(app.router);
+
+    // Error handler
+    if('development' === app.get('env')) {
+      app.use(express.errorHandler())
+    }
   });
 };