Commented lines appear in the output

If we have a less file such as

```javascript
@low: red;
//@low: blue;
```

The output will be `{low: "blue"}`

I understand that the issue is caused by:
https://github.com/michaeltaranto/less-vars-to-js/issues/7

However, they do not seem like fixing this bug, and it seems relatively to fix as part of this package.

Thanks!!