Allow default zone description to be changed

Removed the section of code that was blocking the default
zone description to be changed.

https://bugzilla.redhat.com/show_bug.cgi?id=1098305
To make the zone selection work the way it did before, this line needs to push an array with both name and description, allowing the description to be shown, but the name to be sent up when the user makes a choice (select_tag can take a hash or an array with text for drop down, select value):
```ruby
      @edit[:server_zones].push([zone.description, zone.name])
```
If only description is used like you have it, then when that is sent up, the controller does a find by name using the description field, gets a nil, and the summary screen for the EMS fails with a nil error looking up @ems.zone.name.