Need to register default values for userdefaults before first load; otherwise we get crashes because things like hobbs row isn't on but it thinks it's on

[ericberman]

Repro:

• New install of app
• Hobbs and engine start are visible.
• Add a flight start
• navigate away from the app or restart it
• Re-open the app: note that hobbs and engine start have disappeared!
• Edit the flight start
• Tap "done"
• ==> Crash, because there is inconsistency about whether hobbs (and its row) is present.