code: function Discover(userAddress) {
    return new Promise((resolve, reject) => {
  
      if (userAddress in cachedInfo) {
        return resolve(cachedInfo[userAddress]);
      }
  
      var webFinger = new WebFinger({
        tls_only: false,
        uri_fallback: true,
        request_timeout: 5000
      });
  
      return webFinger.lookup(userAddress, function (err, response) {
        if (err) {
          return reject(err);
        } else if ((typeof response.idx.links.remotestorage !== 'object') ||
                   (typeof response.idx.links.remotestorage.length !== 'number') ||
                   (response.idx.links.remotestorage.length <= 0)) {
          log("[Discover] WebFinger record for " + userAddress + " does not have remotestorage defined in the links section ", JSON.stringify(response.json));
          return reject("WebFinger record for " + userAddress + " does not have remotestorage defined in the links section.");
        }
  
        var rs = response.idx.links.remotestorage[0];
        var authURL = rs.properties['http://tools.ietf.org/html/rfc6749#section-4.2'] ||
                      rs.properties['auth-endpoint'];
        var storageApi = rs.properties['http://remotestorage.io/spec/version'] ||
                         rs.type;
  
        // cache fetched data
        cachedInfo[userAddress] = {
          href: rs.href,
          storageApi: storageApi,
          authURL: authURL,
          properties: rs.properties
        };
  
        if (hasLocalStorage) {
          localStorage[SETTINGS_KEY] = JSON.stringify({ cache: cachedInfo });
        }
  
        return resolve(cachedInfo[userAddress]);
      });
    });
  }
docs: This function deals with the Webfinger lookup, discovering a connecting
  user's storage details.
  
  @param {string} userAddress - user@host
  
  @returns {Promise} A promise for an object with the following properties.
  href - Storage base URL,
  storageApi - RS protocol version,
  authUrl - OAuth URL,
  properties - Webfinger link properties