Add scatter over time chart and use CartoDB data

![scatter-over-time](https://cloud.githubusercontent.com/assets/6386/5265147/4599a42c-7a0e-11e4-8481-0bfea4a3c4d2.png)

Also nice. Let's definitely use this pattern in the future.

Here's a good quick summary of var vs function hoisting that everyone should read if not already familiar:
http://designpepper.com/blog/drips/variable-and-function-hoisting