Extend the admin urls for the CompetitionEntryAdmin model
            to be able to invoke a CSV export view  on the admin model

def get_urls(self):
        """ Extend the admin urls for the CompetitionEntryAdmin model
            to be able to invoke a CSV export view  on the admin model """
        urls = super(CompetitionEntryAdmin, self).get_urls()
        csv_urls = patterns('',
            url(
                r'^exportcsv/$',
                self.admin_site.admin_view(self.csv_export),
                name='competition-csv-export'
            )
        )
        return csv_urls + urls