Please add guardian-supervisor-strategy tot he Fluent API

[stevemesser]

We are trying to update our application to use the Fluent API for configuration and after asking about this Aaron suggested creating an issue for it.

We would to be able to configure the following via the Fluent API:

akka { actor { guardian-supervisor-strategy = "BatchProcessorLibrary.Akka.GuardianSupervisorStrategy, BatchProcessorLibrary" } }