don't contact greeters on reconnect

Ignore-this: 50bf0257210db69648dc38fd873957d2

I am going to migrate the ping functionality to either the connection manager or
the udp connection. I will transition away from tcp for the greeter.

Another option is to write a teardown at the tcp connection level in connection manager.
Still undecided...

darcs-hash:20131029172634-c21fe-5d1b922f0a7a4d2c89b5d6ee21784312348b769f