code: function removeSystemProperties(instance) {
      var copy = {};
      for (var property in instance) {
          if ((property != MobileServiceSystemColumns.Version) &&
              (property != MobileServiceSystemColumns.UpdatedAt) &&
              (property != MobileServiceSystemColumns.CreatedAt) &&
              (property != MobileServiceSystemColumns.Deleted))
          {
              copy[property] = instance[property];
          }
      }
      return copy;
  }
docs: Table system properties