<code> have overflow on x-axis on small resolution

Hi, I have PR for `<code>` wrap bug.
With small resolution I have overflow on x-axis (see at screenshot or [check this page](http://theaqua.github.io/social-buttons.scss) (resize window, f.e.)) 

![code nowrap bug](http://gm4.in/i/fud.jpg)

I have 2 solutions:
* Add new class like `code.wrap` with `white-space: pre-wrap`.
* Or on small resolution made `white-space: pre-wrap` as default property.