CreateJS/TweenJS — pull request #52 by ritz4-5 (2014-11-08 10:55:19+00:00)
Title: Fixes bug duration variable in wait and to method

Hi.

Although duration of _addStep must pass a number , I think must casts kicked to a number in the case of String that can be converted to a number.

exp.
```javascript
createjs.Tween.get(target).wait(1000).to({alpha:0}, “1000”).duration // => ”10001000"
```

I think the result is that should be 2000 because animation correctly move(2000msec)