Battery status-based ON_AC uses faulty logic

[luke-jr]

        if [ $FOUND_SYS_CLASS_POWER_SUPPLY_AC != 1 ] && [ $BATTERY_NOT_DISCHARGING = 1 ]; then

But BATTERY_NOT_DISCHARGING can only ever be set if FOUND_SYS_CLASS_POWER_SUPPLY_AC is also being set. Should FOUND_SYS_CLASS_POWER_SUPPLY_AC=1 be moved inside the "Mains" check??

[rickysarraf]

This must be the effect of #116

Wherein you don't have a usual power supply subsystem.

[rickysarraf]

Closing this issue, for #116