EmotionAll MVP

Users can choose from a list of trends in our database and see a heat map of the world based on the sentiment of tweets for that particular trend. 
A model really shouldn't be responsible for creating json.  That should happen in a controller or, better yet, a [presenter](http://blog.jayfields.com/2007/03/rails-presenter-pattern.html) or decorator (like [Draper](https://github.com/drapergem/draper)).