Added Regex to remove JSON.NET '$ref' and '$id' properties

Fixes #553

Before:
![before](https://cloud.githubusercontent.com/assets/582487/3008879/3f55e7d0-ded5-11e3-9566-07d9ff4da959.png)

After:
![after](https://cloud.githubusercontent.com/assets/582487/3008880/437dfbea-ded5-11e3-9db5-09e63924f721.png)