Correctly parse app stack in both formats at creation

Before:

```
Creating dodging-samurai-42 in organization acme-widgets-123... done, stack is {"name"=>"cedar", "id"=>"7e04461d-ec81-4bdd-8b37-b69b320a9f83"}
```

After:

```
Creating dodging-samurai-42 in organization acme-widgets-123... done, stack is cedar
```