Exposed {read,write}Js functions on the JS side.

So I just started using this today and it worked well instantly. Very quick to get up and running. Nice work man!

On the JS side, my code goes through [Lift](http://liftweb.net)'s ajax handler and it parses the json response for me. What I need to deserialise ends up being a JS object instead of a JSON string. To handle that scenario `read` wouldn't work, I extracted `read`'s inner `walk` method and called it `readJs`.