The API of your configuration could use some work. Have you looked at the validations present in JSON Schema[1]?

Instead of

  {
    "commit": {
      "message_must_be_imperative_tense": true,
      "message_must_include_prefix": {
        "prefixes": ["feat", "fix", "docs", "refactor"],
        "require_after_prefix": " "
      }
    }
  }

Something like:

  {
    "commit": {
      "message": {
        "imperative": true,
        "prefixes": ["feat ", "fix ", "docs ", "refactor "]
      }
    }
  }

[1] http://json-schema.org/latest/json-schema-validation.html