Removing "cc.associateWithNative" since it isn't needed anymore.
Removing some unused codes.
Merge remote-tracking branch 'dumganhar/remove-associate-nativeobj'

Conflicts:
	games/MoonWarriors/src/AboutLayer.js
	games/MoonWarriors/src/Bullet.js
	games/MoonWarriors/src/Enemy.js
	games/MoonWarriors/src/Explosion.js
	games/MoonWarriors/src/HitEffect.js
	games/MoonWarriors/src/SettingsLayer.js
	games/MoonWarriors/src/Ship.js
	games/MoonWarriors/src/SysMenu.js
	tests/SpriteTest/SpriteTest.js