ISPN-3982 TransactionTable leaks memory when JTS is activated

* Some implementation has an unstable hash code. Use instead the identityHashCode()
ISPN-4446 Signal components of cache removal

* Since stop() takes no parameters, make the remove cache command
signal components of cache removal before cache stop, so that they can
do their job.

Conflicts:
	core/src/main/java/org/infinispan/commands/RemoteCommandsFactory.java
	core/src/main/java/org/infinispan/commands/RemoveCacheCommand.java
	core/src/main/java/org/infinispan/persistence/manager/PersistenceManager.java
	core/src/test/java/org/infinispan/persistence/BaseStoreFunctionalTest.java