code: function(downloadUrl, manifestUrl, flavor) {
          return getManifest(manifestUrl)
              .then(function(manifest) {
                  return {
                      desiredVersion: manifest.stable.replace('v', ''),
                      downloadUrl: downloadUrl,
                      manifestUrl: manifestUrl,
                      flavor: flavor
                  }
              })
              .then(this.getVersion);
      }
docs: Gets the latest stable version
  @param {string} downloadUrl
  @param {string} manifestUrl
  @param {string} flavor
  @returns {promise} which resolves to a {Version}