Allow for all media types in css links

Had some issues with media queries and tracked it down to this. Print queries were not evaluating as a result of this. 

i.e.
```
@media print {
   ...
}
```

Might be nice to have something more configurable here in the future, so that a user can specify the desired media type for the sheet. Something along the lines of

```
module.exports = function (path, media) {
    return "<link href='" + path + "' media='" + media + "' rel='stylesheet' type='text/css'/>";
};
```

Although `media='all'` should be sufficient for now.