improve error message for ssh connection exception

[ltalirz]

The exception for connecting with SSH currently has all the parameters passed to paramiko, except for the host (which is kind of important):

try:
    self._client.connect(self._machine, **connection_arguments)
except Exception as exc:
    self.logger.error("Error connecting through SSH: [{}] {}, "
                      "connect_args were: {}".format(exc.__class__.__name__, exc, self._connect_args))
    raise

Let's include the host as well!