Fix created host-only not being returned

The call to "createHostOnlyNetworkInterface" in
"IHost.create_host_only_network_interface()" returned progress and
host_interface objects in a different order than expected.
I tested this fix with VirtualBox 4.3.14.
Fix __doc__ not being replaced
Merge pull request #22 from wndhydrnt/fix_host_only_create

Fix created host-only not being returned. Thanks for the PR @wndhydrnt.