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.
Actually... `log_check_call` does exactly what you are looking for: https://github.com/andsens/bootstrap-vz/blob/047ae8ebb124460936546b35814a0dce9e2244ed/bootstrapvz/common/tools.py#L6