Message "Mark As Unread" feature for gmail imap client

[Rajiv]

Gmail4j now supports mark message as unread functionality for gmail
imap client. This new feature can be used used as the following:
GmailConnection conn = new ImapGmailConnection();
//configure connection
GmailClient client = new ImapGmailClient();
client.setConnection(conn);
// now get a read GmailMessage item and pass it's message number
client.markAsUnread(message..getMessageNumber());

This feature could be used with Gmail4J Next.
see (http://code.google.com/p/gmail4j/issues/detail?id=19)