code: func (m *Message) saveToDB(db *mgo.Database) error {
  	return db.C("messages").Insert(m)
  }
docs: /*func (im *IncomingMessage) ButtonAnswer(db *mgo.Database) (key string, text string) {
  	if im.Message.ReplyToMsgID == 0 {
  		return
  	}
  
  	om, err := im.ReplyToMessage.FindOutgoingMessage(db)
  	if err != nil || om == nil {
  		return
  	}
  	if val, ok := om.Buttons[im.Text]; ok {
  		return val, im.Text
  	}
  	return
  }*/