Add "node_modules" folder to .gitignore

https://code.google.com/p/esprima/issues/detail?id=482
Make npm test work on Windows and ignore node_modules directory

https://code.google.com/p/esprima/issues/detail?id=490
Update ESLint to 0.3.0.

https://code.google.com/p/esprima/issues/detail?id=473