Add output of a result in the 'nova interface-attach'
command when it is successful.
Make the following methods return a 'NetworkInterface'
object instead of a 'Server' object.
* The 'interface_attach' method
in the 'novaclient.v2.Server' class
* The 'interface_attach' method
in the 'novaclient.v2.ServerManager' class
Remove unnecessary code in the 'nova interface-detach'
command because the response body is not returned.
Change-Id: Id5316d8ad4a4b67e8399b51e602aafc83bc128c6
Closes-Bug: #1816511
7e56102201