upgrade to denominator 1.2.1: better error message when -Z arg doesn't match what's on the server

Now existing zone names are returned, in case you had a typo.

```
$  denominator -p route53 -c AAAA -c SSSS record -z adrianc.zone.route53test.jclouds.org list
;; error: zone adrianc.zone.route53test.jclouds.org not found in [Zone{name=myzone.com., id=Z3I0BTR7N27QRM}, Zone{name=adrianc.zone.route53test.jclouds.org., id=Z1KWEIO71EBZIB}, Zone{name=adrianc.zone.route53test.jclouds.org., id=ZO6XA7CYZ0IBA}, Zone{name=dyntest.netflix.net., id=Z1VO4BIB35Q8HU}]
```