RfxCom Lightning6 message added

Hello,

I added support for the lightning6 messages (Blyss protocol) in the RFXCOM binding.
The syntax with Openhab is :
 Lighting6 format: ```SensorId.GroupCode.UnitCode``` e.g. 257.B.1, 64343.B.2 or 636602.H.5

It works with my Blyss Switch, but probably not with Blyss motors which use 2 extra internal Command Seq Number as it is described in the RFX documentation.
Can you integrate this code in the RFXCOM binding ?

Thanks,

Damien