Some development boards like M5Stick-C have inverted LED, so
when pin HIGH - led is off , etc.
To support that we need minor changes in code, unfortunately i dont have
other boards, but inverted LED can be added to other senders
easily.
Tested on Gree A/C and M5Stick-C.
Signed-off-by: Denys Fedoryshchenko <denys.f@collabora.com>