Fix 665 ssh debug log

Fix #665 - provision/docker/ssh: add debug logs

Is not logging responses, but better than nothing:
```
2014/03/24 16:48:39 DEBUG: Running SSH on docker01.mycloud.tld:4545: [ -f /home/application/apprc ] && source /home/application/apprc; [ -d /home/application/current ] && cd /home/application/current; ps aux []
```