Obscure EC2 creds

The introduction of the Python InfrastructureManager caused the EC2 cloud variables `CLOUD1_EC2_ACCESS_KEY` and `CLOUD1_EC2_SECRET_KEY` to be renamed to `CLOUD_EC2_ACCESS_KEY` and `CLOUD_EC2_SECRET_KEY`. Therefore, this causes credentials to be printed to stdout (as the AppController's obscure_creds function wasn't changed to match this change). This pull fixes that oversight.