[install] Show admin password warning only when superuser is first created

Created by: nemesisdesign

The message added in #35 now is always shown, also on subsequent upgrades.

It would be better to show this message only when the superuser is created, we have a variable we can use for this.

so it would be just a matter of adding something like this to the debug msg:

when: '"created" in load_initial_data_result.stdout'