A Patch to Control the Charset of the FTP Server

[689854847]

Generally there is a bug for Windows Explorer on Chinese Windows Platforms that 
when decoding UTF-8 lines the last byte will be cut out and will ususally cause 
an error like a wrong filename. A work-around for this bug is to make the 
server using GBK and tell Windows not to use UTF-8. Currently Apache Mina 
FtpServer supports UTF-8 only, so I made this patch to make it possible to 
control it. 
 
Thank you for review the patch.