account for the newline as well
- don't build keygen anymore (lumberjack2's protocol design is delayed
for now)
- use `` string literals for struct tags. Lets me do `json:"ssl
  certificate"` for worded json keys
- use int64 (offsets can be negative in seek calls)
- Allow harvesters to start up at a given file offset
- use publishv1 (the original lumberjack protocol)
- support stdin again
- restart any known files at their previous positions as recorded by the
registrar.
finish implementing lumberjack protocol in lumberjack2 (test works
against logstash 1.1.13)

This has one slight behavioral change from the C version. We now
send a window size change before every spooled payload. This has
the effect of allowing slow publishers to be acknowledged sooner.