Geofence & notification updates

-User alerted to dock when they reach the ideal station when it has >0
docks or an alternate station when it has >0 docks and the ideal
station has 0 docks. Station tracking stops automatically at this time
-Geofence functions separated into entry & exit to differentiate for
the above feature
-Station update alerts play sound/vibrate (new bike bell sound effect
added)
-Updated title for station update alert view
-Action sheet appears to confirm navigation to a station after pressing
the map annotation callout button
-Comment cleanup