Allow the server port to be configurable via config.js

sample.config.js

@@ -1,4 +1,5 @@
 var config = {
+  port: 3000,
   db: {
       user      : '',
       password  : '',

server.js

@@ -16,7 +16,7 @@ app.configure(function() {
   app.use(express.errorHandler({dumpExceptions: true, showStack: true}));
 });
 
-var port = 3000;
+var port = config.port;
 server.listen(port, function() {
   console.log( 'Express server listening on port %d in %s mode', port, app.settings.env );
 });