Sort order: Make array of strings an acceptable value (#127)

Issue #127

In config you can now use `sort-order: [ 'top', 'color' ]` instead of `sort-order: [ [ 'top', 'color' ] ]`

![jcvtuo5](https://f.cloud.github.com/assets/872004/1755190/8d19caa6-6660-11e3-9635-48d7dccca959.gif)