Improve `get` output

Having `name` and `domain` as separate keys isn't really useful. Update the get command to output something like this:

``` shell
➜  ~ floaty get centos-7-x86_64
{"centos-7-x86_64": "wfkcu6ompyf68xh.delivery.puppetlabs.net"}
```

``` shell
➜  ~ floaty get centos-7-x86_64=2
{"centos-7-x86_64": ["1.delivery.puppetlabs.net", "2.delivery.puppetlabs.net"] }
```
