INT-3305 SFTP Connect Error Polishing

* Add code to test to wait for server to start
* Avoid NPE when trying to close a Sesion that was never open
INT-3288 Increase Test Timeouts

JIRA: https://jira.spring.io/browse/INT-3288

Sometimes, even locally with no load, ActiveMQ takes over
5 seconds to deliver the message with a polled adapter.

Increase timeout to 20 seconds instead of 2.
INT-3288 Increase receive-timeout

JIRA: https://jira.spring.io/browse/INT-3288

Block in the ActiveMQ client for each poll instead
of returning immediately.
INT-3315 Use Non-Peristent AMQ Broker for Tests

JIRA: https://jira.spring.io/browse/INT-3315

Some tests use a persistent broker which can cause crosstalk
between tests/test runs.