Fixes #1536

Cleaned up code in UnicastBus to remove the audit related properties, which have been moved to the Audit feature. Related to #1399 

With these changes, I ran the unit tests, the NHibernate unit tests failed on my machine and I had set the NH related app.settings properties in these files and then the tests passed. 
https://github.com/Particular/NServiceBus/blob/develop/src/nhibernate/SagaPersister/NServiceBus.SagaPersisters.NHibernate.Tests/App.config
https://github.com/Particular/NServiceBus/blob/develop/src/nhibernate/Subscriptions/NServiceBus.Unicast.Subscriptions.NHibernate.Tests/App.config

Do I need to do anything special that will let me pass these tests without changing my config??