Open connection to remote host.

def _open(self):
        """ Open connection to remote host. """
        if self._process is not None:
            return

        cmd = [
            'ssh',
            self._host,
            'sudo',
            'buttersink',
            '--server',
            '--mode',
            self._mode,
            self._directory
        ]
        logger.debug("Connecting with: %s", cmd)
        self._process = subprocess.Popen(
            cmd,
            stdin=subprocess.PIPE,
            stderr=sys.stderr,
            # stdout=sys.stdout,
            stdout=subprocess.PIPE,
        )

        version = self.version()
        logger.info("Remote version: %s", version)