Trap errors for invalid account when authorizing an Herirloom

@thbishop could you please take a look at this change and provide feedback? This addresses issue https://github.com/intuit/heirloom/issues/57

I am having problems getting the spec test I created to pass, I think I am overlooking something.

Bad Account:
```
2013-11-04 12:24:23 -0800 DEBUG : Proxy environment variable https_proxy not set.
2013-11-04 12:24:23 -0800 DEBUG : Domain 'kevin' exists in 'us-west-1'.
2013-11-04 12:24:25 -0800 DEBUG : Found entry for v0.0.1 in SimpleDB.
2013-11-04 12:24:25 -0800 INFO : Using kevin_young1@intuit.com for authorization
2013-11-04 12:24:25 -0800 INFO : Authorizing kevin_young1@intuit.com.
2013-11-04 12:24:26 -0800 DEBUG : Looking for bucket in us-west-1 for v0.0.1
2013-11-04 12:24:26 -0800 DEBUG : Found entry for v0.0.1 in SimpleDB.
2013-11-04 12:24:26 -0800 DEBUG : Looking for us-west-1 endpoint for v0.0.1
2013-11-04 12:24:27 -0800 DEBUG : Found us-west-1-s3-url for v0.0.1.
2013-11-04 12:24:27 -0800 DEBUG : Found bucket young-us-west-1.
2013-11-04 12:24:28 -0800 DEBUG : Authorizing kevin_young1@intuit.com to s3://young-us-west-1/kevin/v0.0.1.tar.gz.
2013-11-04 12:24:28 -0800 ERROR : The e-mail address you provided does not match any account on record.
2013-11-04 12:24:28 -0800 INFO : Authorization complete.
```

Good Account:
```
2013-11-04 12:23:54 -0800 DEBUG : Proxy environment variable https_proxy not set.
2013-11-04 12:23:54 -0800 DEBUG : Domain 'kevin' exists in 'us-west-1'.
2013-11-04 12:23:55 -0800 DEBUG : Found entry for v0.0.1 in SimpleDB.
2013-11-04 12:23:55 -0800 INFO : Using kevin_young@intuit.com for authorization
2013-11-04 12:23:55 -0800 INFO : Authorizing kevin_young@intuit.com.
2013-11-04 12:23:56 -0800 DEBUG : Looking for bucket in us-west-1 for v0.0.1
2013-11-04 12:23:56 -0800 DEBUG : Found entry for v0.0.1 in SimpleDB.
2013-11-04 12:23:56 -0800 DEBUG : Looking for us-west-1 endpoint for v0.0.1
2013-11-04 12:23:56 -0800 DEBUG : Found us-west-1-s3-url for v0.0.1.
2013-11-04 12:23:57 -0800 DEBUG : Found bucket young-us-west-1.
2013-11-04 12:23:58 -0800 DEBUG : Authorizing kevin_young@intuit.com to s3://young-us-west-1/kevin/v0.0.1.tar.gz.
2013-11-04 12:23:58 -0800 DEBUG : Looking for bucket in us-east-1 for v0.0.1
2013-11-04 12:23:58 -0800 DEBUG : Found entry for v0.0.1 in SimpleDB.
2013-11-04 12:23:58 -0800 DEBUG : Looking for us-east-1 endpoint for v0.0.1
2013-11-04 12:23:59 -0800 DEBUG : Found us-east-1-s3-url for v0.0.1.
2013-11-04 12:23:59 -0800 DEBUG : Found bucket young-us-east-1.
2013-11-04 12:24:00 -0800 DEBUG : Authorizing kevin_young@intuit.com to s3://young-us-east-1/kevin/v0.0.1.tar.gz.
2013-11-04 12:24:00 -0800 DEBUG : Looking for bucket in us-west-2 for v0.0.1
2013-11-04 12:24:01 -0800 DEBUG : Found entry for v0.0.1 in SimpleDB.
2013-11-04 12:24:01 -0800 DEBUG : Looking for us-west-2 endpoint for v0.0.1
2013-11-04 12:24:01 -0800 DEBUG : Found us-west-2-s3-url for v0.0.1.
2013-11-04 12:24:02 -0800 DEBUG : Found bucket young-us-west-2.
2013-11-04 12:24:02 -0800 DEBUG : Authorizing kevin_young@intuit.com to s3://young-us-west-2/kevin/v0.0.1.tar.gz.
2013-11-04 12:24:03 -0800 INFO : Authorization complete.
```