Fixes #5

Not ready for merging. Here for review. See #5 and https://github.com/yeoman/yo/pull/167. Better ideas are welcome!
Ok, I'm kinda dumb.

The replace function is being called with:

```js
arguments = { '0': '\u001b[31m',
  '1': '31',
  '2': undefined,
  '3': 0,
  '4': '\u001b[31mhi\u001b[39m' }
```