CustomerListController.m is a table view controller that displays the
customer data in the client database. The viewWillAppear method uses the Object API to query
the database for a list of all Customer objects, and builds an NSArray that is used by this
class as the data source for displaying the table view.
If a row is tapped, the accessoryButtonTappedForRowWithIndexPath method is run, which pushes
a DetailController onto the stack to display additional information and allow the data to be
modified.