Add host to polling message

The message for when an async task has finished has the hostname in it. This adds it to the polling message as well:

```
<job 390794962174.18311> finished on 107.6.24.140
<job 390794962174.31779> finished on 69.90.50.171
<job 390794962174.12328> polling on 69.90.50.172, 6840s remaining
```