Implement a Syslog Source

[blt]

Cernan could be a pretty decent syslog. But! We've to date assumed that you'll pipe logs in by dropping them on disk first. Maybe we oughtn't.

[tfheen]

https://crates.io/crates/syslog_rfc5424 + a UDP and TCP listener shouldn't be terribly hard to put together. Might want to support more syslog formats later too.

[blt]

@tfheen I'd be very interested to see this work done. syslog_rfc5424 would need updating, I think. rustc_serialize is deprecated in favor of serde but the update shouldn't be a nightmare show.

[tfheen]

I've started looking slightly at this, and since I'd like to support the various syslog formats, I'm looking at nom. Thoughts, opinions, etc?

[blt]

I think that'd be a perfect use-case for nom. I've used nom in past days to parse in the statsd and graphite sources, backing it out for something hand-rolled since those formats are simple enough. Syslog seems like it hits the sweet-spot of complexity for using nom.