Next verion of the crtauth protocol

* introduce msgpack_protocol which creates messages of the new
  version
* the new format encodes version information into all emitted messages
* update signing semantics slightly (we now sign the full challenge
  not just a subset)
* update AuthServer to work seamlessly with both versions
* improved unit tests
Update copyright years
Merge pull request #10 from noaresare/pr/msgpack-version

Next verion of the crtauth protocol