Revert "Minor tidy-up around type and annotations."

This reverts commit d1e5c1adb175104e95db578d8b3001c906f247ea.
https://issues.jboss.org/browse/JBTM-2048

Add explanation of how invalid states are handled during activation.
https://issues.jboss.org/browse/JBTM-2059

Added NestedTopLevel annotation so new transactions that are top level
will be created by the container. Added a test too.
Revert "JBTM-1936. Add XNIO dependency where managed Arquillian container is used"

This reverts commit 7ef5c75d10d3b35675e5762bbafb82c796b623e9.