removing libftp as it can't support sessions without a lot of work
Removed the other ftplib in favor of a different ftplib implementation that does not cache hostname information. This allows multiple sessions to be opened to the same FTP server. I have also updated the library to copy the servent and the hostent. This makes the Ftp* methods thread-safe (as the servent and hostent data is cached by their respective methods and would be clobbered on subsequent calls methods such as gethostbyname()).
Added 430 FTP error.
Updated readme