Feature / BC break: Change Request methods to be in line with PSR-7 (#117 by @clue)

• Rename getQuery() to getQueryParams()
• Rename getHttpVersion() to getProtocolVersion()
• Change getHeaders() to always return an array of string values for each header

Feature / BC break: Update Socket component to v0.5 and add secure HTTPS server support (#90 and #119 by @clue)

// old plaintext HTTP server
$socket = new React\Socket\Server($loop);
$socket->listen(8080, '127.0.0.1');
$http = new React\Http\Server($socket);

// new plaintext HTTP server
$socket = new React\Socket\Server('127.0.0.1:8080', $loop);
$http = new React\Http\Server($socket);

// new secure HTTPS server
$socket = new React\Socket\Server('127.0.0.1:8080', $loop);
$socket = new React\Socket\SecureServer($socket, $loop, array(
    'local_cert' => __DIR__ . '/localhost.pem'
));
$http = new React\Http\Server($socket);

BC break: Mark internal APIs as internal or private and remove unneeded ServerInterface (#118 by @clue, #95 by @legionth)