[COOK-4237] Nginx version incorrectly parsed on Ubuntu 13

https://tickets.opscode.com/browse/COOK-4237

When installing Nginx from default repository on Ubuntu 13 (both Ubuntu 13.04 and Ubuntu 13.10), nginx command prints the distribution name following the version number.

```shell
$ nginx -v
nginx version: nginx/1.4.1 (Ubuntu)
```

So node[:nginx][:version] ends up with "1.4.1 (Ubuntu)".