Fix daemon logs so that "API listen on" is INFO not ERROR

W/o this PR the logs would show:
```
ERRO[0000] API listen on [::]:2375
ERRO[0000] API listen on /var/run/docker.sock
```
which is misleading since these aren't "errors" they're just informational.

Signed-off-by: Doug Davis <dug@us.ibm.com>