Feature: Add request header accessors (à la PSR-7)
(#103 by @clue)

// get value of host header
$host = $request->getHeaderLine('Host');

// get list of all cookie headers
$cookies = $request->getHeader('Cookie');

Feature: Forward pause() and resume() from Request to underlying connection
(#110 by @clue)

// support back-pressure when piping request into slower destination
$request->pipe($dest);

// manually pause/resume request
$request->pause();
$request->resume();

Fix: Fix 100-continue to be handled case-insensitive and ignore it for HTTP/1.0.
Similarly, outgoing response headers are now handled case-insensitive, e.g
we no longer apply chunked transfer encoding with mixed-case Content-Length.
(#107 by @clue)

// now handled case-insensitive
$request->expectsContinue();

// now works just like properly-cased header
$response->writeHead($status, array('content-length' => 0));

Fix: Do not emit empty data events and ignore empty writes in order to
not mess up chunked transfer encoding
(#108 and #112 by @clue)

Lock and test minimum required dependency versions and support PHPUnit v5
(#113, #115 and #114 by @andig)