BugFix: ensure to save groupDnProperty

lib/form/admin/securityPassportLdap.js

@@ -17,6 +17,7 @@ module.exports = form(
   field('settingForm[security:passport-ldap:searchFilter]'),
   field('settingForm[security:passport-ldap:attrMapUsername]'),
   field('settingForm[security:passport-ldap:groupSearchBase]'),
-  field('settingForm[security:passport-ldap:groupSearchFilter]')
+  field('settingForm[security:passport-ldap:groupSearchFilter]'),
+  field('settingForm[security:passport-ldap:groupDnProperty]')
 );