"Para usar o aplicativo..." error message behaviour #16
Description
Currently, the app asks for configurations (if not yet entered) as soon as it opens.
This message (and the configuration screen) should be activated (if needed) only when user press the "Generate Invoice" button.
This will make the app less annoying and consistent (why ask for information that the user probably doesn't have yet and it's not needed right now?).
This also will allow the use of the application as a simple and practical BTC<->fiat conversion tool while it's not fully configured.