Returns the additional urls used by the Reversion admin.

def get_urls(self):
        """Returns the additional urls used by the Reversion admin."""
        urls = super(SimpleHistoryAdmin, self).get_urls()
        admin_site = self.admin_site
        opts = self.model._meta
        info = opts.app_label, opts.model_name
        history_urls = [
            url(
                "^([^/]+)/history/([^/]+)/$",
                admin_site.admin_view(self.history_form_view),
                name="%s_%s_simple_history" % info,
            )
        ]
        return history_urls + urls