Zigate firmware 3.1a

[pipiche]

Firmware 3.1a has been release, works perfectly and do not required to erase PDM/EEPROM and so do not need to redo the pairing.

As the firmware do not provide any benefits to Plugin 4.3 (currently on stable branch), The firmware has not bee verified on stable/4.3 branch and will not be supported.

Please switch to 'beta' branch 4.4 if you like to move to this firmware.