Add kafka-subscribe and kafka-publish commands

*kafka-subscribe* and *kafka-publish* are command line programs to help in
the task of debugging a kafka installation.

For example, send the syslog to kafka

```
tail -f /var/log/syslog | kafka-publish -t syslog
```

or

```
sudo nc -l 514 -u | kafka-publish -t syslog-server
```

or

```
kafka-subscribe -t weather_channel > weather_channel.log
```

But the main intention was to have something to debug easily kafka
streams.