Bug#793463: powerdevil is necessary to not use powerdevil

[Salvo Tomaselli <tiposchi@tiscali.it>]

Apparently powerdevil is necessary to NOT use power management.

After installing powerdevil, the checkbox about disabling power management 
actually works. Without installing powerdevil, the screen will be locked after 
a timeout and there is no way to stop or configure that.

I find it a bit weird, I suppose that the screen locking functionality should 
be moved inside powerdevil.
-- 
Salvo Tomaselli

"Io non mi sento obbligato a credere che lo stesso Dio che ci ha dotato di 
senso, ragione ed intelletto intendesse che noi ne facessimo a meno."
                -- Galileo Galilei

                http://ltworf.github.io/ltworf/