Broken/dead links found in README

[tracedynamics]

Hi! I was scanning the README for broken links and found these:

1. http://thinkster.io - DNS resolution failed (domain no longer resolves, listed in JavaScript section)
2. http://sahatyalkabov.com/create-a-character-voting-app-using-react-nodejs-mongodb-and-socketio - 404 (React/Node.js tutorial)
3. http://dev.stephendiehl.com/fun/ - Connection timed out (Haskell tutorial)

Would you be open to a PR that replaces these with working alternatives? Happy to submit one.