Backwards compatible node module

The Node module now supports multi urls, but in this change it
stopped supporting the old syntax for single urls. Before merging
to master I want the old syntax supported again.

The README also has to be updated with the new syntax.

---
* [X] Add back support for `url: 'http.mysite.com'` parameter.
* [X] Add back support for `css` parameter, either separately, or by reverting the `cssFile` name change.
* [x] Update `README`