@ashfurrow => standardise staging and the default auction id

Moved to keep the our defaults in a single place. This could be thrown in the defaults for staging switches in admin etc at a later date.

Aside: I was surprised to find that the`let AuctionID = "ici-live-auction"` in `AppDelegate.swift` was being accessed from `ListingsViewController.swift` figured they'd be private by default.
this is an interesting pattern, it took me a few seconds to figure out what's going on here, very sneaky ;)