Wow, bringing down total tests from 202 to 10.

```js
todd at Euclid in ~/github/grunt-spritesmith on master
$ npm test

> grunt-spritesmith@1.6.2 test /home/todd/github/grunt-spritesmith
> cd src-test && grunt

Running "sprite:default" (sprite) task
Files "scratch/sprite_positions.styl", "scratch/sprite.png" created.
...
Running "nodeunit:all" (nodeunit) task
Testing grunt-spritesmith.test.js......OK
>> 202 assertions passed (11ms)

Done, without errors.
todd at Euclid in ~/github/grunt-spritesmith on master
$ git checkout -
Switched to branch 'pr/28'
todd at Euclid in ~/github/grunt-spritesmith on pr/28
$ npm test

> grunt-spritesmith@1.6.2 test /home/todd/github/grunt-spritesmith
> cd src-test && grunt

Running "sprite:default" (sprite) task
Files "scratch/sprite_positions.styl", "scratch/sprite.png" created.
...
Running "nodeunit:all" (nodeunit) task
Testing grunt-spritesmith.test.js......OK
>> 10 assertions passed (15ms)

Done, without errors.
```