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
Close channel on accept exception
INT-2620 Fix Race Condition in Failover Tests