TYRUS-367 causes reverse DNS lookup for every opened session - reverting for now.

Revert "TYRUS-367: UtilsTest.validateConnectionProperties fixes + tests."
Revert "TYRUS-367: review, refactoring (naming, error reporting, TyrusSession and test modification)"
Revert "TYRUS-367: Provide a way how to get low-level info about the session"

This reverts commit 85fd42373f4aefdd3d8314a9fd3b0d5d32ebfada.
This reverts commit bf5953f1232692cb0a9de966f19e1e6f0e8b89dd.
This reverts commit 1680cc6eead648b452f7e0aadcf2ffe860748af9.
reverting @Ignore on IPv6EchoTest - caused by TYRUS-367 impl.

This reverts commit 7e8063ecda5c505c1c3596817bf30616d809dd40.
TYRUS-381: addMessageHandler(Class, MessageHandler.Whole<Class>) produced invalid error message.

(when user was trying to register message handler without appropriate decoder).