Better logging needed when we run out of file descriptors

The problem is that our server stops responding if you run out of file descriptors. If the soft limit equals the hard limit, we will continue to use FD's until we cannot get anymore. Unfortunately, this causes access to hang rather than us refusing connections when we reach a limit.

We need to make it easier to diagnose what is happening when you run out of file descriptors.

-There need to be messages in our logs
-We should be refusing connections when out of FD's instead of just hanging
(and also increment the refused connections stat)
-We should reserve at least one FD/connection so that a user can connect to the
server and still get stats to see that the connections are being refused