fix image and atlas resource not found #141, #147
fix image and atlas resource not found #141, #147

merged patches issue 141(atlas) by martijn.faassen, issue 147(image) by lucascaro
Thanks, guys !

vyscond/cocos,dangillet/cocos,shujunqiao/cocos2d-python,shujunqiao/cocos2d-python,shujunqiao/cocos2d-python