fixes #4 specify multiple upload files

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
fixes spelling error

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
fixes #6 support to retrieve multiple objects

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>