OpenSRF client disconnect robustification (Perl)

* Improve detection of client connection state with jabber server

  Be more aggressive in testing and responding to failed connectivity.
  It can happen in various ways, depending on what's happening to the
  jabber server (death, delay, graceful shutdown).  With these changes
  we attempt to cover all the bases and detect as early as possible that
  a connection has died, specifically when trying to create a new
  connection after one has failed.

* Do a better job of cleaning up dead connections

  Transport::PeerHandle now has a reset() action which disconnects (when
  possible) and clears the global connection reference.

Signed-off-by: Bill Erickson <berick@esilibrary.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>