Added commenting to AppDelegate connecting to Parse and initiating significant location change monitoring on start up.
Prevent segue to drop item view controller if current location is not known.
Exposed AppDelegate’s locationManager so that location info is more easily available.
Made AppDelegate the Tab Bar Controller delegate in order to make the Collect tab selectable only if a valid location is available.
Inventory view controller no longer needs to receive location change notification as it can consult the AppDelegate’s locationManager for that info before deciding to allow/disallow a segue to the Drop Item view controller.