lib/appdir.js
function _findNested (d) {
  let nested = [];
  walk.walkSync(d, (basedir, filename, stat) => {
    const file = path.join(basedir, filename);
    if (file.indexOf('.app/Info.plist') !== -1) {
      const nest = file.lastIndexOf('.app/');
      nested.push(file.substring(0, nest + 4));
    }
  });
  return nested;
}
function _findNested (d) {
  let nested = [];
  walk.walkSync(d, (basedir, filename, stat) => {
    const file = path.join(basedir, filename);
    if (file.indexOf('.app/Info.plist') !== -1) {
      const nest = file.lastIndexOf('.app/');
      nested.push(file.substring(0, nest + 4));
    }
  });
  return nested;
}
return an array of strings with the absolute paths of the sub-apps found inside appdir