'juju add-cloud' should prompt for credentials

[John A Meinel]

I just registered a new MAAS cloud, which had this interaction:
$ juju add-cloud
Cloud Types
  maas
  manual
  openstack
  vsphere

Select cloud type: maas

Enter a name for the cloud: maas21

Enter the API endpoint url: http://localhost:8080/MAAS

Cloud "maas21" successfully added
You may bootstrap with 'juju bootstrap maas21'

However, trying to do that fails with:
15:09:51 ERROR cmd supercommand.go:458 detecting credentials for "maas21" cloud provider: maas credentials not found

Giving a hint about how to add credentials would probably be better than giving a hint that you can bootstrap. Though I guess if we get "bootstrap" to also prompt for a credential when you don't have one, that might be ok.

[Anastasia (anastasia-macmood)]

The message after a cloud has been added successfully has changed to say:

You will need to add credentials for this cloud (`juju add-credential <new cloud name>`)
before creating a controller (`juju bootstrap <new cloud name>`).