function getManifest(manifestUrl) {
  let chunks = undefined;

  return new Promise((resolve) => {
    const req = https.get(manifestUrl, (response) => {
      response.on('data', (chunk) => {
        chunks += chunk;
      });

      response.on('error', (e) => {
        console.error(e);
        resolve(undefined);
      });

      response.on('end', () => {
        resolve(chunks);
      });
    });
    req.on('error', (e) => {
      console.error(e);
      resolve(undefined);
    });
  });
}
Get manifest (array of NW release metadata) from URL.
@param  {string}                      manifestUrl  Url to manifest
@returns {Promise<object | undefined>}              - Manifest object