WFLY-456 Audit log fixes

I did not check these before the WildFly 8.0.0.Alpha4 release

1) I hadn't fixed properly trying to remove an audit log handler reference when booted with enabled=false, so I have done this properly and added a test. Previously this would fail with a message saying there was an attempt to both add and update a handler reference

2) The JMX subsystem had not been updated to take into account that the core audit logging configuration was moved to /core-service=management/access=audit