AMQP-361 Fix Javadocs for JDK8

JIRA: https://jira.springsource.org/browse/AMQP-361
AMQP-364 Revert Long MesageProperties to long

API changes to support the message builder (with setIfAbsent) breaks
existing Apps. Use a boolean instead to determine if the header has been
explicitly set.

JIRA: https://jira.springsource.org/browse/AMQP-364

Cause: 22801e674f0e0c401d055a145381573308785790
AMQP-363: Fix `ignoresThrowable` for AmqpAppender

JIRA: https://jira.springsource.org/browse/AMQP-363

Previously the `AmqpAppender` didn't check `layout.ignoresThrowable`
and added `ThrowableInformation` to the end of log message.

* Add check `layout.ignoresThrowable()` and now it allow to use custom `Layout`, e.g. JSON or XML
* Add test for `org.apache.log4j.xml.XMLLayout`

Polishing: stop container after test.
AMQP-365 Fix Test Race Condition; Polish Shutdown

JIRA: https://jira.springsource.org/browse/AMQP-365

See the JIRA issue for a description of the race condition.

Also, these tests destroy the connection factory while the
container is still running (it is stopped in the After method
which is after the factory was destroyed).

This identified a further problem with container shutdown in
that the concwsumertainer never receives a cancel() and hence the
container thinks a force close is needed.

* Fix the race condition as described in the JIRA
* Count down the `activeObjectCounter` when a shutdown signal is received
* More polish on the shutdown logging; don't log a stack trace (even under DEBUG) for
    a "normal" close - extract the common logic to `RabbitUtils`

AMQP-365 Polishing

Test failed because logger.debug is now different - this caused
a container to loop and create a huge log file.
AMQP-366 StackTrace for ConsumerCancelledException

Do not emit a stack trace for this exception (which can
result, for example, when the consumer's queue is deleted).

It is only thrown from one place.

JIRA: https://jira.springsource.org/browse/AMQP-366
AMQP-367: Add `removeConnectionListener`

JIRA: https://jira.springsource.org/browse/AMQP-367