I was getting the following error when i set the scan_interval
```
self.scan_interval = timedelta(seconds=config.get(CONF_SCAN_INTERVAL, 60))
TypeError: unsupported type for timedelta seconds component: datetime.timedelta
```
it turns out `config.get(CONF_SCAN_INTERVAL)` already returns `timedelta`
```('scan_interval', datetime.timedelta(seconds=180))```