add winSize variable define.

When I used the IDE "JetBrains WebStorm 8.0.3" to debug the tutorial's code above, I found in the BackgroundLayer.js and StatusLayer.js file, the variable winSize is undefined,so I should first define it through adding extra code "var winSize = cc.Director.getInstance().getWinSize();", the project code provided at last link "https://github.com/chukong/cocos-docs/blob/master/tutorial/framework/html5/parkour-game-with-javascript/chapter4/res/Parkour.zip" is ok while the tutorial's code is not correct!
Merge pull request #333 from ccf19881030/patch-2

fix code error: add variable winSize's define.