getCacheBuster () {
    return this.options.ajax_cache_buster || new Date().toISOString().slice(0, 10)
  }
Returns the schema cache buster from JSON Editor settings.

@returns {string}
  The configured cache buster, if any. Otherwise, returns the current date
  in ISO 8601 simplified format (e.g., 2011-10-05 for October 5, 2011).