GF-40308: Add allowHighlanderDeactivate prop to Group

Enyo-DCO-1.1-Signed-off-by: Jeremy Thomas <jeremy.thomas@lge.com>
Merge pull request #509 from enyojs/GF-40308-jeremythomas

GF-40308: Add allowHighlanderDeactivate prop to Group

Reviewed-By: Ben Combee (ben.combee@lge.com)