Fix log_check_call in docker_daemon.

This fixes the log_check_call usage in proppy's pull_images task.

It also cleans up the docker.sock to prevent errors during the cleanup stage.
Yeah, it checks the return code. This is inside a retry loop, though. we could leave it as log_check_call with a try: except: wrapping it, or move it to log_call like I did here.

The main bug is that log_check_call will never return the return_code, so the comparison to 0 doesn't work.