Remove .navbar-collapse padding when not in mobile context

Before:
![screen shot 2013-08-14 at 11 37 59 am](https://f.cloud.github.com/assets/1933700/962878/d1ac0bc2-04f7-11e3-9180-d4cf5f6994c2.png)

After:
![screen shot 2013-08-14 at 11 38 28 am](https://f.cloud.github.com/assets/1933700/962879/d4e62912-04f7-11e3-9a76-ce60c032c253.png)