Add option to show username on top of posts instead of the left gutter

![screen shot 2014-04-05 at 6 58 10 pm](https://cloud.githubusercontent.com/assets/31063/2622772/82b8e22c-bcc8-11e3-8a6d-cca83d46a77c.png)
![screen shot 2014-04-05 at 6 58 25 pm](https://cloud.githubusercontent.com/assets/31063/2622773/84f0d266-bcc8-11e3-9bda-5c9dc888038b.png)