rmlint writes non-compliant JSON if quotes are passed at the command line

If you set `-o json` and your command contains `"`, the json will look like

```
"args": "rmlint path1 path2 --rank-by=mplaO --no-followlinks --keep-hardlinked -o json:asdf.json -o pretty:stdout -o summary:stdout -o sh:asdf.sh -c sh:cmd=.asdf.sh "$1" "$2"",
```

`$2"",`

is not compliant - the " is not escaped. JSON parsers fail on this.