Fixed

• \Http\Adapter\Guzzle6\Client::sendRequest no longer throws any exceptions that do not implement the PSR exception interface.

  Instead of \UnexpectedValueException we now throw Http\Adapter\Guzzle6\Exception\UnexpectedValueException (which extends \UnexpectedValueException and implements Psr\Http\Client\ClientExceptionInterface).

  Instead of \RuntimeException we now throw Http\Client\Exception\TransferException (which extends \RuntimeException and implements Psr\Http\Client\ClientExceptionInterface).