Storyarrays: Always return an array of story

No story
```bash
callback: { '0': null, '1': { story: [] } }
```

1 Story
```bash
callback: { '0': null, '1': { story: [ [Object] ] } }
```

2 Stories
```bash
callback: { '0': null, '1': { story: [ [Object], [Object] ] } }
```