Adds statistics methods to repo

@mikedeboer I was doing some work with GitHub statistics and saw #131 sooo close to being merged. It looks like the previous owner gave up so I thought I'd give it a shot to finally get these in. I fixed the outstanding typo and added the corresponding tests.

Before (old PR):
![screen shot 2014-11-17 at 9 18 45 pm](https://cloud.githubusercontent.com/assets/6980359/5082867/5a1b9e2a-6e9f-11e4-8b6e-2d301084c26f.png)

After (fixed below):
![screen shot 2014-11-17 at 9 17 53 pm](https://cloud.githubusercontent.com/assets/6980359/5082868/601f73b4-6e9f-11e4-975e-33b9adf8f736.png)