* version 0.02 12/11/2007
  - Removed procfs support since /proc/acpi will be removed from kernel soon.
  - Added sysfs support.
  - Button states are now unified into a single attribute file which displays
    the button name used to power the system on.
  - Added attribute file to show all suported buttons.
  - Code cleanups.

* version 0.01 10/11/2007
  - Detects button devices and creates proc entries to each device.
  - Proc entries can be written.
  - Workaround to raise device Notify event.