Replace Create factory methods with constructors

https://github.com/mono/cocos2d-xna/issues/117
https://github.com/mono/cocos2d-xna/issues/118
https://github.com/mono/cocos2d-xna/issues/119
https://github.com/mono/cocos2d-xna/issues/120
https://github.com/mono/cocos2d-xna/issues/121
https://github.com/mono/cocos2d-xna/issues/122
https://github.com/mono/cocos2d-xna/issues/17