Bug 16001 - Use standard message dialog when there are no cities to list

Bug 16001 - Use standard message dialog when there are no cities to list

If there are no existing cities in Administration -> Cities and Towns,
the message saying so should be in the standard message dialog.

Another minor change: Edit the message to say "There are no cities
defined," which I think reads better in English.

To test you must have no cities and towns defined.

Apply this patch and go to Administration -> Cities and Towns. You
should see a message displayed in a standard "message" style dialog.

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Better view, no errors

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>