Per PR comment:
> I'm running simple 1-channel led dimmer and couldn't get brightness control working, as it was called only if lightHasColor().
> This PR changes conditions slightly, and allows domoticz's dimmer device to control brightness as well. I think this device type is more appropriate/comfortable in this case."
- remove lightHasColor() check, try to parse the payload and manually adjust the channels
- when domoticz payload does not have "Color" field, still fall-through to the brightness update