title: RichFileManager configuration Json error
body: <p>I have been trying to use the <a href="https://github.com/servocoder/RichFilemanager" rel="nofollow noreferrer">Rich file Manager</a> but Im stuck at initial loading with the following error in the browser console; I do not understand why and could not find any documentation on this issue. the RFM folder is located at <code>cc/admin/RichFilemanager</code>.</p>
  
  <pre><code>json: E_INVALID_PAR_TYPE: {"expected":"Plain Object","name":"json","value":"{\n  \"main\": {\n    \"en\": {\n      \"identity\": {\n        \"version\": {\n          \"_number\": \"$Revision: 13744 $\",\n          \"_cldrVersion\": 
  </code></pre>
  
  <p>here is my filemanager.init.js that has the default config from github:</p>
  
  <pre><code>$('.fm-container').richFilemanager({
  // options for the plugin initialization step and callback functions, see:
  // https://github.com/servocoder/RichFilemanager/wiki/Configuration-options#plugin-parameters
  
  baseUrl: '/cc/admin/RichFilemanager',
  
  callbacks: {
  beforeCreateImageUrl: function (resourceObject, url) {
      return url += 'modified=ImageUrl';
  },
  beforeCreatePreviewUrl: function (resourceObject, url) {
      return url += '&amp;modified=previewUrl';
  },
  beforeSelectItem: function (resourceObject, url) {
      return url += '&amp;modified=selectItem';
  },
  afterSelectItem: function (resourceObject, url) {
      // example on how to set url into target input and close bootstrap modal window
      // assumes that filemanager is opened via iframe, which is at the same domain as parent
      // https://developer.mozilla.org/en-US/docs/Web/Security/Same-origin_policy
      $('#target-input', parent.document).val(url);
      $('#modal', parent.document).find('.close').click();
  },
  beforeSetRequestParams: function (requestMethod, requestParams) {
      // add "jwt" parameter with "your_token" value to both GET and POST requests
      if (requestMethod === 'POST' &amp;&amp; $.isArray(requestParams)) { // form parameters
          requestParams.push({name: "jwt", value: "your_token"});
      } else {
          requestParams.jwt = 'your_token';
      }
      return requestParams;
  },
  beforeSendRequest: function (requestMethod, requestParams) {
      // prevent all GET requests that lack "jwt" request parameter
      if (requestMethod === 'GET' &amp;&amp; requestParams.jwt === undefined) {
          return false;
      }
      return true;
  }
    }
  });
  </code></pre>