Update to latest msgpack

[jbruggem]

The current implementation of msgpack-hadoop is not compatible with the latest version of msgpack (0.6.7).

Our company has updated part of the codebase to be compatible, but we're still missing two things that we haven't updated:

• the Test cases.
• the whole Hive part.

We also took the liberty to make the implementation able to use split files (which is not the case in the current version).

Is it still worth a pull request, so at least part of the code is up to date?

See our implementation here: https://github.com/Technicolor-Portico/msgpack-hadoop