bucket: bucket_create() should not need an argument named `name'
main: test for bucket::delete_bucket();
main: handle exception: socketexcept && unhandled exception
vs13: default to multibyte charset
main: read alioss.key from file or stdin
1. for windows: alioss.key should in the same folder of executables.
2. for Linux: alioss.key should in the `HOME' folder.