escape image name
escape image name

```
docker save minimum2scp/ruby:latest > /home/ubuntu/.cache/docker/minimum2scp/ruby:latest.tar
sh: 1: cannot create /home/ubuntu/.cache/docker/minimum2scp/ruby:latest.tar: Directory nonexistent
```

minimum2scp/ruby-binary,minimum2scp/ruby-binary,minimum2scp/ruby-binary