App is a map

* Finish set up of Rails so it runs properly
* Set up basic Mapbox API situation
* Show my shiny new New York map

This is just showing a basic map. Next PR will be pulling in the data.
You can use figaro if you'd like. I have a personal preference to dotenv mostly because to me it more closely replicates how heroku deals with environment variables. It's very easy to move around and does not have a requirement on yaml.

That said, figaro does do the exact same thing.