Rubyize json

The JSON wasn't really ruby like, keys in the returned JSON could be anything, i.e. `weatherForecast` instead of `weather_forecast`

This subclasses `Hashie::Mash` to allow for a custom key transformer.

![uyfob1n](https://f.cloud.github.com/assets/103217/1624169/0efd28a4-56be-11e3-8422-ca041ee66f3b.gif)