Acquisio/bootstrap-stylus — pull request #1 by luccamordente (2013-02-08 17:18:14+00:00)
Title: Allowing variables to be overriden by user

By adding 'unless' to each variable like:

```css
$black = #000 unless $black;
$grayDarker = #222 unless $grayDarker;
$grayDark = #333 unless $grayDark;
$gray = #555 unless $gray;
```