Counters for successful/failed healthchecks

Got counters working for successful/failed healthchecks.

They're currently rudimentary, but they allow you to tweak some settings on a VIP that dictate how many failures before marking a service DOWN, and how many successes before marking it UP. With this change, services can begin their lives disabled, which is desired nehavior.
Non-working HTTP listener

The request to the Load Balancer is being copied to the service correctly, but then when we try to write the content back to the client, we get an error that tells us that we're trying to write more than the declared Content-Length. Blah.