google map showing points rendered by d3

# this is the one to review

> if you want to test this out just 
- grab the branch, 
- go into the `spike\d3_gmaps` folder 
- and run `shotgun app.rb`
- then open http://localhost:9393 to view the map
> 
> note that the json is just coming from a local file right now but will come from sinatra later

**zoomed out version showing US locations with graffiti-related tags from instagram**

![screen shot 2013-11-14 at 5 50 30 pm](https://f.cloud.github.com/assets/24913/1547214/68fe6cd4-4d98-11e3-8ce6-362452577799.png)

**zoomed in version showing Sao Paolo with same data**

![screen shot 2013-11-14 at 5 50 59 pm](https://f.cloud.github.com/assets/24913/1547215/6a5aca00-4d98-11e3-92ef-641ee4ecd201.png)