remove Encoding::CompatibilityError

exception messages will be utf8 all the time
(servers can return in different encoding type)
add port to connect to
fix dakuon(濁音, in Japanese) in filename problem

merges dakuon into one letter

か + ゙ => が
Merge branch 'ftp_port_missing'
Merge branch 'osx_filename_problem'
Merge branch 'master-github'