Get rid of navbar-brand margin-right

Is there a purpose to the margin-right on the `navbar-brand` class?

Before: 
![screen shot 2013-08-14 at 12 58 35 pm](https://f.cloud.github.com/assets/1933700/963465/870920b2-0503-11e3-82cf-015d6fcd360f.png)

After:
![screen shot 2013-08-14 at 12 58 55 pm](https://f.cloud.github.com/assets/1933700/963466/8c1ee190-0503-11e3-90eb-92eee3b6a3d2.png)


Web Inspector
![screen shot 2013-08-14 at 12 55 10 pm](https://f.cloud.github.com/assets/1933700/963468/945f6136-0503-11e3-9d91-235799cef1c4.png)

![screen shot 2013-08-14 at 12 56 12 pm](https://f.cloud.github.com/assets/1933700/963470/a22f1cd4-0503-11e3-8ae8-eaf3da79687e.png)