Incorrect drawing bar chart with data hide when init since v0.4.15

## What version of C3?
- v0.4.15
- This problem was not produced at v0.4.14

## Reproduce code

fiddle: http://jsfiddle.net/p7q596yu/

```js
var chart = c3.generate({
data: {
type: 'bar',
columns: [
['data1', 100, 200, 150, 300, 200],
['data2', 400, 500, 250, 700, 300],
],
hide: ['data2']
}
});
```

### Rendered image

### Expected image