Squashed commit of the following:

commit 6cce32f6a3ea6eb70d3e4edb5c6edef24993d1ca
Author: Clay Stewart <claytonmstewart@gmail.com>
Date:   Fri Sep 20 14:25:23 2013 -0500

    Add a method to the Train class to calculate the distance based on the duration
Add a method to calculate trip distance.

[Closes #2]