Added feature discovery as per RFC 2389.
Added feature discovery as per RFC 2389.

runner-mei/ftp,jlaffaye/ftp,catalint/ftp,catalint/ftp,runner-mei/ftp,justintung/ftp,sunvim/ftp,SoheilSalehian/ftp,Mojachieee/ftp,etix/goftp,Mojachieee/ftp