DNS Manager update

With this edit I enabled administrators (from group ID 1) to manage any DNS domain, even if not owned by himself.
I did this change because using the "shadowing" feature while having DNS Manager disabled for users doesn't let anyone to edit DNS values of the treated domain
![sentora-dns-update](https://cloud.githubusercontent.com/assets/4939519/5113712/febbd164-7031-11e4-9f49-9c3914fbbf7c.jpg)