Add custom uuid type.
The uuid is represented by a 16-byte long NSData object (NSUUID support planned).

The msgpack_src was replaced by a submodule dependency to a forked msgpack-c repository. For more details about uuid support check commit:

https://github.com/laugga/msgpack-c/commit/87a47c09e8bbe3674d6a44f861ea0fb7a1943fcd