Added some tests from json.org

Hi, I noticed you don't have any tests or examples, so I made you a test runner that could serve as one and added the test files from http://www.json.org/JSON_checker/. Unfortunately your lib doesn't actually pass all of them. :frowning:

I also made you a Travis:
[![Build Status](https://travis-ci.org/Lexicality/Jzon.png?branch=master)](https://travis-ci.org/Lexicality/Jzon)
Which you should be able to set up on your own repo with [one or two simple steps](http://about.travis-ci.org/docs/user/getting-started/) if you want