Fix deprecated warning

```
Warning: Variable access via 'env_variables' is deprecated. Use '@env_variables' instead. template[/etc/puppet/modules/apache/templates/virtualhost/vhost.conf.erb]:17
   (at /etc/puppet/modules/apache/templates/virtualhost/vhost.conf.erb:17:in `result')
```
Merge pull request #63 from marcospassos/patch-1

Fix deprecated warning