ISPN-3803 Stale locks during state transfer in non-tx caches

Clean up SingleKeyNonTxInvocationContext and allow the key to be
locked/unlocked independently of whether the entry was looked-up or not.
Undo lost comments and CDATA sections from POM introduced by maven-release-plugin during 6.0.1 release
Change version to 7.0.0-SNAPSHOT

Also remove unnecessary groupId (already inherited from parent)