Removed outline when hovering over links.

* outline is removed when hovering over links
* outline still exists in the drop down (unfortunately)

Previously with outline:
![outline](https://cloud.githubusercontent.com/assets/5265058/4958866/22b6d2a4-66b3-11e4-9924-33f4984584d8.png)

Proposed update without outline:
![no-outline](https://cloud.githubusercontent.com/assets/5265058/4958867/22b78e60-66b3-11e4-9b7d-ce5f62ffc3e3.png)

I didn't spend too much time on this and made a small improvement in removing the outline when hovering over links.

@rocha @clintonb @marcotuts @shnayder