INT-2982 Fix Hard-Coded Ports in Syslog Tests

Use the port finder to find an available port; using
hard-coded ports can cause issues with concurrent builds.

One test found a port in the XML but was still hard-coded
in the test itself rather than retrieving the port from
the adapter.

Also, stop the adapters when tests complete.
Merge pull request #790 from garyrussell/INT-2982a

* garyrussell-INT-2982a:
  INT-2982 Fix Hard-Coded Ports in Syslog Tests
INT-2620 Fix Race Condition in Failover Tests

Sporadic test failures (fairly consistently on Mac).

Problem was some tests sent a message to a client socket before the
close notification had been received.

Wait for client connection to close rather than waiting for the
server to stop.

Also, with NIO, close the channel on accept exception.

Also improve debugging by including a log of new connections
including the id.
Merge pull request #793 from garyrussell/INT-2620

* garyrussell-INT-2620:
  INT-2620 Fix Race Condition in Failover Tests
INT-2991 Filtered Messages Marked SEEN

Missing else clause caused filtered email messages to
still be marked as SEEN. Also marked un-filtered messages
twice if a filter was present.

Add else; add tests.
Merge pull request #784 from garyrussell/INT-2991

* garyrussell-INT-2991:
  INT-2991 Filtered Messages Marked SEEN