ec2-key-pair went away, but juju doesn't say it is unsupported

[Jamie Strandboge]

Apparently people should be using 'authorized-keys' or 'authorized-keys-path' in environments.yaml. 'ec2-key-pair' is found in google and it would be good if juju checked that it was specified and that people should instead use 'authorized-keys' or 'authorized-keys-path'. This would save people some time.

It might also be nice that the documentation states that juju injects this ssh key differently than EC2 and that people should not expect for the former value of ec2-key-pair to show up in 'euca-describe-instances'. In other words, whey I use 'euca-run-instanaces -k mykey' I expect to see 'running mykey' in 'euca-describe-instances output. With juju, we see 'running None' now, but that is expected with how juju is working (but unexpected if used to EC2).