Feature: Update Browser signature to take optional $connector as first argument and to match new Socket API without nullable loop arguments. (#418 and #419 by @clue)

// unchanged
$browser = new React\Http\Browser();

// deprecated
$browser = new React\Http\Browser(null, $connector);
$browser = new React\Http\Browser($loop, $connector);

// new
$browser = new React\Http\Browser($connector);
$browser = new React\Http\Browser($connector, $loop);

Feature: Rename Server to HttpServer to avoid class name collisions and to avoid any ambiguities with regards to the new SocketServer API. (#417 and #419 by @clue)

// deprecated
$server = new React\Http\Server($handler);
$server->listen(new React\Socket\Server(8080));

// new
$http = new React\Http\HttpServer($handler);
$http->listen(new React\Socket\SocketServer('127.0.0.1:8080'));