Don't HTML-sanitize JSON output

[per1234]

By default, the json package HTML-sanitizes strings during marshalling. This is not useful for this application and resulted in the JSON output containing gibberish.

---

Before:

"rules": [
  {
    "category": "library.properties",
    "subcategory": "author field",
    "ID": "LP024",
    "brief": "author \u003c min length",
    "description": "",
    "result": "fail",
    "level": "error",
    "message": "library.properties author value is less than minimum length."
  },

After:

"rules": [
  {
    "category": "library.properties",
    "subcategory": "author field",
    "ID": "LP024",
    "brief": "author < min length",
    "description": "",
    "result": "fail",
    "level": "error",
    "message": "library.properties author value is less than minimum length."
  }

[ubidefeo]

good!
👍🏼