Create the admin group only on owner creation

For new cloudrons this will first remove the previously added group and
mailbox entry from the db migration scripts and readds it once we have a
domain on owner creation

src/constants.js

@@ -19,8 +19,8 @@ exports = module.exports = {
     ADMIN_NAME: 'Settings',
 
     ADMIN_CLIENT_ID: 'webadmin', // oauth client id
-    ADMIN_APPID: 'admin', // admin appid (settingsdb)
 
+    ADMIN_GROUP_NAME: 'admin',
     ADMIN_GROUP_ID: 'admin',
 
     NGINX_ADMIN_CONFIG_FILE_NAME: 'admin.conf',