incompatible file version throws an exception

prevents the generic assert in addChild because child is nil which doesn't exactly say why this is happening
Joints support collideBodies.
Merge branch 'develop-v3' of https://github.com/apportable/cocos2d-iphone into develop-v3
update cocos2d
Merge branch 'develop-v3' of https://github.com/apportable/cocos2d-iphone into develop-v3