adding unittest-cpp dependency only if enable_test is on for Wkcocos.
fixing android build with strongbox and new external-bin in cocos.
bump cocos2d
Merge branch 'game/dragonfall' of git://github.com/asmodehn/WkCocos into game/dragonfall
Merge branch 'game/dragonfall' into feature/strongbox

Conflicts:
	Android/app/build.gradle
	Android/lib/build.gradle