GNOME has removed 'SetPercentage' dbus interface

[xuhdev]

See here. This dbus interface does not work for me on GNOME 3.14. Have to use the new way (set Brightness variable) to make it work.

[skystrife]

FWIW, the xbacklight backend should still work. I think this is the issue that I was seeing on my machine as well, which motivated PR #44. That PR doesn't fix this issue, but it probably would at least make lightum work on your system again.