Fixed unable to turn on group without setting dim value + other improvements

[slasktrat]

• Fixed unable to turn on group without setting dim value
• Updating group capabilities if lights are changed through scenes or controlled individually
• Added setting on group device to force set dim value on each light individually as the IKEA gateway sometimes stops updating some lights when updated through a group (this issue also occurs in the official IKEA app)

[slasktrat]

Thanks :)