code: function _gpfGetMimeType (fileExtension) {
      var mimeType = _gpfMimeTypesFromExtension[fileExtension.toLowerCase()];
      if (undefined === mimeType) {
          // Default
          mimeType = "application/octet-stream";
      }
      return mimeType;
  }
docs: Retrieve the mime type associates with the file extension (default is "application/octet-stream")
  
  @param {String} fileExtension
  @return {String}