Release Name: 0.5.2

Notes:
* Replaced some missing include's that I thought were unnecessary. Thanks go
  to Liu Song for the spot.
* Changed the license to Artistic 2.0, and set that explicitly in the gemspec.


Changes:
* Replaced some missing include's that I thought were unnecessary. Thanks go
  to Liu Song for the spot.
* Changed the license to Artistic 2.0, and set that explicitly in the gemspec.