Added Feature: Ability to navigate by Read

I've added a feature that I thought was missing, the ability to see what I have read in the past.

![Screen Shot 2013-04-18 at 9 27 26 PM](https://f.cloud.github.com/assets/624483/400135/5602f670-a890-11e2-8aa8-bea8b3567d4a.png)