报错 Image: unsupported image format!
web端是报eror的，原生端直接报错。
Simulator: [ERROR] (/Users/nantas/fireball-x/cocos2d-x-lite_21/cocos/scripting/js-bindings/manual/jsb_global.cpp, 891): initWithImageFile: http://www.molikonglong.com/static/static_1_1_1_2_5/img/52.png failed!
这样导致原生端不能做容错处理，遇资源不对就报错了
