refresh bookings when returning to home view after a delay

[timdrysdale]

when returning to home view after a delay, old bookings are still listed as being valid. refresh this view consider whether to do

• on a timer that refreshes if stale, on user action (don't do just anyway as would load server if pages left open unattended)
• with a filter that is run on mounting (if appropriate hook) that discards expired bookings