Log Message:
Update ruby-msgpack to 1.0.0. From Jonathan Buschmann in
PR pkg/51404.

2016-07-08 version 1.0.0:

* Fix to be able to pack Symbol with ext types
* Fix for MRI 2.4 (Integer unification)

2016-05-10 version 0.7.6:

* Fix bug to raise IndexOutOfBoundsException for Bignum value with
  small int in JRuby

2016-04-06 version 0.7.5:

* Improved support for i386/armel/armhf environments
* Fix bug for negative ext type id and some architectures (arm*)