FTPFileSystem can't rename files in different directory

[Jerry Zhao]

HI, 
I have a confusion about the reason of FTPFilesystem only support same 
directory rename, distCp that from other filesystem copying files to ftp 
filesystem can’t work well, because the distCp write temp files in a temp path, 
then rename files to different directory. I would like to update the logic, Can 
I do this?