Sent FTP/FTPS commands and the received answer is logged at debug level (VFS-459).

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/vfs/trunk@1448560 13f79535-47bb-0310-9956-ffa450edef68
Add support for FTPS command to set the DataChannelProtectionLevel (VFS-412).

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/vfs/trunk@1448606 13f79535-47bb-0310-9956-ffa450edef68