message: don't use npx
  Because it can accidentally troll you when you have a globally cached thing already.
diff: @@ -104,7 +104,7 @@ async function spawnHub(packageName, configPath, environment) {
  let seedDir = path.join(path.dirname(configPath),
  '..', 'cardstack', 'seeds', environment);
  - let proc = spawn('npx', ['cardstack-hub', ...flags, seedDir], { stdio: [0, 1, 2, 'ipc'] });
  + let proc = spawn(path.join(__dirname, 'bin', 'cardstack-hub.js'), [...flags, seedDir], { stdio: [0, 1, 2, 'ipc'] });
  await new Promise((resolve, reject) => {
  // by convention the hub will send a hello message if it sees we
  // are supervising it over IPC. If we get an error or exit before
  