Improvement to setMessageStatus. It is much more terse. It is more functional: using a map, rather than a for-loop

GiftedMessengerContainer.js

  setMessageStatus(uniqueId, status) {
    return this.state.messages.map(function(message) {
      if (message.uniqueId !== uniqueId) {
        return message;
      }
      return Object.assign({}, message, {status});
    });
  }