ALL : Replace super() by the parent __init__ instead for inherited class
Kms : Correct the case where a card exist but no mode are available
Battery : Check in the constructor if the battery exist
CpuFreq : Check in the constructor if the cpu exist
Kms : Check in the constructor if the graphic card exist
Fulgurd : Reduce sleep time + make a constant
Gtk : Create a generic GTK class for all utility GTK functions