Add 'top' and 'bottom' directions.

Possible fix for #47 (fyi @ryansit, astetik).

Wanted to put this up and see what you thought. Some of the CSS could be cleaned up a bit.

![screen shot 2013-11-26 at 12 56 32 am](https://f.cloud.github.com/assets/97697/1619988/c93663d0-5668-11e3-8dd3-82e6b0ddc4ab.png)

What do you think?