v0.7.0

Imported release from original tag date 2022-02-05.

• Feature: Update to use HTTP status code constants and JSON/HTML response helpers.
  (#114 by @clue)

  $app->get('/users/{name}', function (Psr\Http\Message\ServerRequestInterface $request) {
      return React\Http\Message\Response::plaintext(
          "Hello " . $request->getAttribute('name') . "!\n"
      );
  });

• Feature / Fix: Update to improve protocol handling for HTTP responses with no body.
  (#113 by @clue)

• Minor documentation improvements.
  (#112 by @SimonFrings and #115 by @netcarver)