Release Name: 0.6.1

Notes:
* Fix for OS X 10.5


Changes:
* Fix for OS X 10.5.x. Thanks go to Victor Costan for the spot and the patch.
* Updated the gemspec and some other minor changes.
* On MS Windows the impersonation level is now explicitly set to 'impersonate'
  to avoid issues where systems might be using an older version of WMI.