fix(logger): add back message tag

without the tag, the first word from the logs was missing.

Without this change:

    2014-07-23 16:29:05 oblong-duckling[worker.1]:  world

with this change:

    2014-07-23 16:38:19 oblong-duckling[worker.1]: hello world

closes #1400

I also formatted the logger module correctly with `go fmt`.
Well I think we really need to figure out the bug in the rsyslog capture (as that should definitely be part of the message, not the tag). Could you file a bug to investigate this? For now, this fixes it so I'm happy. LGTM.