New Audio Engine[ios/android]

Design Specification: https://docs.google.com/a/cocos2d-x.org/document/d/1aQdB16BkKyLBFg-DFVqhrZ5VWsf70eY0bbArEOycDoM/edit

The completed parts:2d audio on ios/android.
know issues：
[android]: Unable to get duration of  Ogg file.
invokingCallbacks is invoked in if and else, so should be changed like

```c++
if (_queBufferFrames > 0) {
        _alBufferReady = true;    
}
invokingCallbacks();
```