A native node addon for obtaining system idle time in seconds. OS implementations derived from the following resources: http://www.danandcheryl.com/2010/06/how-to-check-the-system-idle-time-using-cocoa https://github.com/jojobyte/idlerun https://github.com/rosedu/Pidgin/blob/master/pidgin/gtkidle.c