unlink is not working.

react-native: 0.58.5
react-native-fs: 2.13.3

test it on simulator IPad Air2 and device IPad

My file path:

`file:///var/mobile/Containers/Data/Application/14E28AC2-5E35-4749-B09F-75DBEB0499A4/Library/Caches/Camera/6C6B1C9F-FDAF-4BEB-BEB0-126633336671.jpg`

I save the photo to my device's gallery by this:

```
import { CameraRoll } from 'react-native';

// save it to my device's gallery
CameraRoll.saveToCameraRoll(path);
```

Then I can see the jpg file on my device's gallery.

When I try to delete it

```
if (path !== '') {
RNFS.unlink(path).then(() => {
console.log('DELETED PHOTO');
})
// `unlink` will throw an error, if the item to unlink does not exist
.catch((err) => {
console.log(err.message);
});
}
```

I can see DELETED PHOTO on debug mode. But the picture is still on my device's gallery.

I try to change the delete path like this:

`const filePath = path.split('///').pop() // removes leading file:///`

It is still not working. Any one knows how to fix it ? Thanks.