Version option

Got this working by doing the following....

```
npm install less@beta
mv node_modules\less less\dist\beta
npm install less
```

This installs the beta tag from npm (this can be a version or whatever)
Move the folder from the node_modules to our own folder
Install the stable version back to npm

In the grunt file reference the beta folder: `version: "less/dist/beta"`

Then run `grunt`