fixes #6226 - if only one option for required field on new host page (ex. installation media), then automatically select it

I could use .gsub('_id', '') instead of .humanize, but it will do the nearly the same. I liked .humanize since it adds a space 
```
 > 'smart_proxy_id'.humanize
 => "Smart proxy" 
```
verses
```
> 'smart_proxy_id'.gsub('_id','')
 => "smart_proxy"
```
It's just to generate a string for the 'blank message'. Why does this affect translations?