Indentation incorrect for array at top level

Example:

```python
import jsonstreams

with jsonstreams.Stream(jsonstreams.Type.array, filename='test.json', indent=4) as s:
    s.write({"a": 1, "b": 2})
```

Actual test.json:

```json
[
    {
    "a": 1,
    "b": 2
}
]
```

Expected test.json:

```json
[
    {
        "a": 1,
        "b": 2
    }
]
```