Dead code in swipe recognizer

I believe this
https://github.com/zingchart/zingtouch/blob/d36d10e0a375b5b31e6f6beb3f942c16b4433ee9/src/gestures/Swipe.js#L210

should be 
```JavaScript
for (var i = 0; i < output.data.length; i++) {
        if (output.data[i].velocity < this.escapeVelocity) {
          return null;
        }
      }
```
otherwise, it is useless. 