Log when credentials are wrong / key is rejected

I'm not sure this is something that Pusher ought to do. Basically, I'm using this daemon and the keys were wrong. I noticed that the daemon was using a lot of CPU power. I had to do a `lsof` on the daemon to figure out that the connection to pusher was not being made.

Should Pusher write to the log and complain that the credentials are wrong / a connection can't be made when this is the scenario?
