Site method will initiate SITE command from FTP protocol
specification, together with some command implemented on the server.
This varies from server to server. Usually, servers implement
commands specific to their environment through SITE, such as CHMOD,
CHGRP, QUOTA etc.. You can usually execute HELP command to retrieve
list of all commands supported by the server.
When command completes,
SiteReply
event will be fired with results of the command. In
Blocking mode,
Site method will also return response of SITE command immediately.