jboss.server.exitonshutdown is broken

1) setting the jboss.server.exitonshutdown property is ignored; it's hard-coded to true in org.jboss.Main
2) even if ExitOnShutdown is set to false though the console, the code in ShutdownHook.shutdown() is executed twice, the first time through Server.shutdown(), the second time when the all the non-daemon threads have exited and the Shutdown hook gets activated.

We either need to unregister the shutdown hook on Server.shutdown (which means that forceHalt will not be used in this case, even if set), or mark with a flag that shutdown is already done.

JBossJDKLogManager doReset should probably be performed in ShtudownHook.shutdown()