Log Message:
Update msgpack to 0.5.9.

2014-07-02 version 0.5.9:

  * Support std::tr1 unordered containers by default (#51, #63, #68, #69)
  * Remove some warnings (#56)
  * Fix segmentation fault after malloc failures (#58, #59)
  * Fix alloc/dealloc mismatch (#52, #61)
  * Fix sample codes (#60, #64)
  * Support implicit conversion from integer to float/double (#54)
  * Improve documents (#45, #75, #82, #83)
  * Support CMake (#20, #87)
  * Remove Ruby dependencies in bootstrap (#86, #87)
  * Add FILE* buffer (#40)
  * Other bug fixes and refactoring: #39, #73, #77, #79, #80, #81, #84, #90