NServiceBus version 4 and RavenDB 2.5

If using NServiceBus v4 endpoints and RavenDB 2.5 server is installed, then the user must install the NServiceBus.RavenDB nuget package and initialize appropriately. Added Guidance. Fixes https://github.com/Particular/docs.particular.net/issues/158
Not recommended. Good point. Need to add a little more details on why its not recommended.