code: function(allowedAttributes) {
      var tmp = []
      this.forEach(function(record) {
        tmp.push(record.toJson(allowedAttributes))
      })
      return tmp
    }
docs: Returns an array of objects which represent the records in plain json
  
  @class Collection
  @method toJson
  @param {array} allowedAttributes - Optional: Only export the given attributes and/or relations
  
  @return {array}