proposal: Dead link checker

I was going through the resources and noticed `capacitor` is a dead link. To tackle the general problem, I wrote a script to check the README (`node scripts/checkLinks.js`). It found that the following links are 404s:
- http://revelry.co/2014/11/01/what-you-need-to-know-about-react
- https://github.com/josephsavona/capacitor
- http://todomvc.com/labs/architecture-examples/react-backbone

Note: The script also found three false positives from Quora and tutsplus (Quora does not respond to HEAD, and tutsplus is returning 403), so I guess link cleanup can't be fully automated.