show hostname and ssh_port at list.

`kitchen list` shows Hostname and SSHPort if exists.

```
$ kitchen list
Instance             Driver   Provisioner  Last Action  Hostname   SSHPort
default-ubuntu-1204  Vagrant  ChefSolo     Created      <Unknown>  <Unknown>
default-centos-64    Vagrant  ChefSolo     Created      <Unknown>  <Unknown>
```

```
$ kitchen list
Instance             Driver   Provisioner  Last Action  Hostname   SSHPort
default-ubuntu-1204  Vagrant  ChefSolo     Created      127.0.0.1  2201
default-centos-64    Vagrant  ChefSolo     Created      127.0.0.1  2202
```