acknowledgeMsg (msgNum, userId) {
    return new Promise((resolve, reject) => {
      const options = {
        url: `api/user/${userId}/acknowledge`,
        method: 'PUT',
        data: { msgNum }
      };

      Vue.axios(options)
        .then((response) => {
          resolve(response);
        }, (error) => {
          reject(error);
        });
    });
  }
Acknowledge the welcome message for a user
@param {number} msgNum     The message number
                           { userId, currentPassword, newPassword }
@param {string} userId     The unique identifier for a user
                           (only required if not the current user)
@returns {Promise} Promise A promise object that signals the completion
                           or rejection of the request.