fix to follow renaming flag.


``vdc-manage host show`` results error:

```
$ /opt/axsh/wakame-vdc/dcmgr/bin/vdc-manage host show
ERROR: undefined method `enabled' for #<Dcmgr::Models::HostNode:0x007fdcbf866b60> (/opt/axsh/wakame-vdc/dcmgr/lib/dcmgr/cli/host.rb:99:in `block in show')
```