Detect stale conns when ping times out

Detect stale conns when ping times out

When an ovsdb client connects StalePassiveConnectionService
checks to see if there are any previous connections to that
same client. If there are, they are pinged to determine
whether or not they are still actually connected. The
callback that handles the ping results does not fire
properly in the event of a timeout and the onFailure method
does not call
OvsdbConnectionService.notifyListenerForPassiveConnection
for the new connection. This results in the new connection
not being being reported "up the stack."

Note: easiest way to reproduce this is to "unplug" (destroy
in libvirt) a VM running the OVS and then start it.

Issue: NETVIRT-1178
Change-Id: Ie3494c46719954f862d8edb6e8921a752dcd30ea
Signed-off-by: Josh <jhershbe@redhat.com>