Work around horrible incompatibilities with beaver, logstash

Adding loop-back input to reprocess events with oldlogstashjson codec.
This is required because beaver v30 doesn't generate events with the
logstash 1.2 json schema, the apache logs I'm generating use the old
json schema, the bunyan logs have their own (better) json schema,
logstash's field renaming is broken for nested properties, and there
doesn't appear to be a way to reprocess an existing event through a
codec. *phew*

I'm kinda fed up with logstash right now…