Shh reporting

Gives ehmon the ability to fire reports off to a listening [shh](https://github.com/heroku/shh) process.

It can connect via unix socket, or tcp connection to the listening shh process. Buffering and replay are supported when that connection is lost.

Newb question, but doesn't this mean that we'll silently swallow messages we don't understand? Seems like that could mask subtle bugs, but I'm a bit fuzzy on the best practices for this situation.