1.2.0

Avoid websocket disconnects by sending pings (#8)

* Try to avoid websocket disconnects by sending pings

usage (botman):

```
$loop->addPeriodicTimer(60, function () use ($botman) {
    $timeout = 2.0;
    $botman->getClient()->checkConnection($timeout);
});
```

* Fix logging when detecting timeouts in websocket