Introduce Envelope#toString

Contributed by Michał Kiędyś in
https://github.com/rabbitmq/rabbitmq-java-client/pull/8
Introduce GetResponse#toString
Cover all built in exchange types in testUnbind()
Merge bug26015
Merge bug 26014
stable to default
Bump timeout to 30 minutes
Remove extra assertion
Assert here
and here
Remove a version that's no longer necessary
Simplify
No need to wait for shutdown in most tests
Cosmetics
That return value tells you nothing and is never checked.
Improve JavaDoc
And that's a reason not to like @SuppressWarnings - you add it and then forget to remove it later.
Spelling
Make overriding method connection factory easier
Towards connection recovery tests that handle primary node restarts better