fix config.supports to match listentities object

[lyuzashi]

Not sure if you're accepting pull requests, but thanks for taking a look.

I found commands like entity.setBrightness(0.9) were throwing brightness is not supported errors due to a miss-match between the entity config and these setter methods. I've modified the name of each property in the if statements.

supportsBrightness: jspb.Message.getBooleanFieldWithDefault(msg, 5, false),

if (!this.config.supports_brightness) throw new Error('brightness is not supported');

[tobiasgraf]

I was running into the same issue today and was about to do the same thing, nice PR.

It would be nice if this PR could be merged.