2.0.0-alpha6

• Added: Asynchronous HTTP client. See examples/asyncclient.php.
• Fixed: Issue #4: Don't escape colon (:) when it's not needed.
• Fixed: Fixed a bug in the content negotation script.
• Fixed: Fallback for when CURLOPT_POSTREDIR is not defined (mainly for hhvm).
• Added: The Request and Response object now have a __toString() method that
  serializes the objects into a standard HTTP message. This is mainly for
  debugging purposes.
• Changed: Added Response::getStatusText(). This method returns the
  human-readable HTTP status message. This part has been removed from
  Response::getStatus(), which now always returns just the status code as an
  int.
• Changed: Response::send() is now Sapi::sendResponse($response).
• Changed: Request::createFromPHPRequest is now Sapi::getRequest().
• Changed: Message::getBodyAsStream and Message::getBodyAsString were added. The
  existing Message::getBody changed it's behavior, so be careful.