std::vector<unsigned char> and std::array<unsigned char> are mapped to BIN.
std::vector<uint8_t> and std::array<uint8_t> are mapped to BIN if uint8_t is the same type of unsigned char, otherwise mapped to ARRAY.
Added array_ref. When client wraps BIN mapped types above with array_ref as msgpack::type::array_ref<std::vector<char> >, the type is mapped to ARRAY.
