Persist & use shake-to-cheat config on phone

Sends a message when the configuration dialog gets saved, only hides
background if shake-to-cheat is enabled
Load and persist config on phone app
Fetch config from phone if not available

This will be the case if the app is uninstalled or updated: if the local
storage system does not have the configuration available, the watchface
will trigger the phone app to send the configuration and persist it
afterwards.