Acquisio/bootstrap-stylus — pull request #2 by luccamordente (2013-02-08 18:20:40+00:00)
Title: Allow variables to be overriden by user

By adding 'unless' to each variable like:

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

This way the user can do something like:
```css
$linkColor = #F00;
```
before importing bootstrap