service object to write out config files

config/application.yml.sample

@@ -10,6 +10,9 @@ defaults: &defaults
   client_key: client-id
   secret_key: client-secret
   callback_url: local-callback
+  htpasswd: "/path/to/vsftpd/password.file"
+  ftpusers: "/path/to/vsftpd/users/configs"
+  ftproot: "/path/to/root/ftp/prefix/"
 
 development:
   <<: *defaults