message: made CORS headers more specific
diff: @@ -85,7 +85,6 @@ class Authentication {
  ctxt.state.cardstackSession = session;
  }
  }
  - addCorsHeaders(ctxt.response);
  await next();
  };
  }
  @@ -196,7 +195,7 @@ class Authentication {
  return route.post(`/${prefix}/:module`, compose([
  koaJSONBody({ limit: '1mb' }),
  async (ctxt) => {
  - ctxt.response.set('Access-Control-Allow-Origin', '*');
  + addCorsHeaders(ctxt.response);
  await withJsonErrorHandling(ctxt, async () => {
  let source = await this._locateAuthenticationSource(ctxt.routeParams.module);
  await this._invokeAuthenticationSource(ctxt, source);
  @@ -207,6 +206,7 @@ class Authentication {
  _exposeConfiguration(prefix) {
  return route.get(`/${prefix}/:module`, async (ctxt) => {
  + addCorsHeaders(ctxt.response);
  await withJsonErrorHandling(ctxt, async () => {
  let source = await this._locateAuthenticationSource(ctxt.routeParams.module);
  if (source.authenticator.exposeConfig) {
  