get all installed zealder apps/themes
function getPackages(app, cb = null) {
  let stdout = '';
  const ls = spawn('npm', ['ls', '--json', '--prod', '--depth=0', '--long']);
  ls.stdout.on('data', data => {
    stdout += data;
  });
  ls.stderr.on('data', data => {
    app.error(`stderr: ${data}`);
  });
  ls.on('close', (code) => {
    if (0 !== code) app.error('child process exited with code %s', code);
    app.debug('loading installed zealder packages');
    var p = JSON.parse(stdout);
    if (p.dependencies) {
      // now set packages to state
      setPackagesState(app, p.dependencies, cb);
    }
  });
}