Missing .name and .mode attributes

The [FileIO attributes](https://docs.python.org/3/library/io.html#io.FileIO) `.name` and `.mode` are missing from the wrappers.

So this works:

```python
with open(filename) as f:
    print(f.name, f.mode)
```

This doesn't, resulting in attribute errors.

```python
async with aiofiles.open(filename) as f:
    print(f.name, f.mode)
```
