Added Mac / OSX support to the Extension

Added support for the MAC. This utalizes the excallent wrapper library
https://github.com/derekvanvliet/Xbox360ControllerManager.git for the
drivers writen by Tattiebogle (
http://tattiebogle.net/index.php/ProjectRoot/Xbox360Controller ). This
builds on the great work done by http://www.baysidegames.net/blog/?p=94