Making the new Audit feature backwards compatible.

 If AuditConfig is not defined in app.config or set in the registry, the feature will be considered disabled.
Messages will be forwarded if the FRM is set in the UnicastBusConfig.
If both FRM is set & the registry/audit config is specified then 2 messages will be forwarded to the audit queue.
Don't log a warning when values are configured in the registry, unless until, audit is turned on and the value  being used is the one from the registry.
Fixed the acceptance testing framework to initialize the configuration source first.

This was causing the audit related acceptance tests to fail, because of the order of initialization.
Audit configuration should be added only if ForwardReceivedMessagesTo attribute in UnicastBus config is not set.
Added better instructions on how to transition over to the new audit
feature
Fixed a typo in the add audit config command
Merge pull request #1611 from Particular/auditSpike

Audit spike