code: function filterData(data) {
          var filteredData = ghostBookshelf.Model.filterData.apply(this, arguments),
              extraData = _.pick(data, this.prototype.relationships);
  
          _.merge(filteredData, extraData);
          return filteredData;
      }
docs: Manually add 'tags' attribute since it's not in the schema and call parent.
  
  @param {Object} data Has keys representing the model's attributes/fields in the database.
  @return {Object} The filtered results of the passed in data, containing only what's allowed in the schema.