support (partial) for bin format family

[blackwithwhite666]

Hi!

This patch add support (partial) for https://github.com/msgpack/msgpack/blob/master/spec.md#bin-format-family. Only unpack is implemented, because i don't know what lua type should be mapped to bin{8,16,32}. If there is one - let me know :)

[tp7]

Will this ever get accepted?

[muzuiget]

About the packing fix, please read https://github.com/antirez/lua-cmsgpack/issues/34 the comment which I post.