Merge pull request #2553 from pandamicro/develop

Add 3.2 changelog
Add compatible codes to cc.Audio for IE didn't trigger 'canplaythrough' event
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-html5 into setTransform
Merge pull request #2554 from dingpinglv/setTransform

Add compatible codes to cc.Audio for IE didn't trigger 'canplaythrough' event
Update build.xml to 3.2