Fix root path argument for wandb.restore() (#818)
Fix root path argument for wandb.restore() (#818)

Fixes #808

Testcode:

```python
import wandb, os
import tempfile

with tempfile.TemporaryDirectory() as t:
    f = wandb.restore('config.yaml', root=t, run_path="borisd13/colorizer/runs/dckzfkk5", replace=True)
    expected = os.path.join(t, 'config.yaml')
    actual = f.name
    assert expected == actual
```
wandb/client,wandb/client,wandb/client