static-favicon depreciated. updated dependencies to serve-favicon

The static-favicon has been depreciated and causes error on on npm start. I suggest changing to the new module serve-favicon.

The only change needed I noticed on your tutorial is to update the snippet code for the package.json.
http://cwbuecheler.com/web/tutorials/2014/restful-web-app-node-express-mongodb/

Reason for change:
running npm install: npm WARN deprecated static-favicon@2.0.0-alpha: use serve-favicon module