Allow reactor modules to be entered directy as manual action implemenations.

[jimsynz]

We already have this for generic actions, however in some cases one may want to simulate a CRUD action using a Reactor. It's easy enough to do by making a custom action implementation, however we can same folks some hassle by allowing a reactor module to be specified as the action definition and run it using a built-in action implementation.

[zachdaniel]

My only hesitation here is that generic action modules can have multiple callbacks, which could make it a hassle to switch to a non-reactor solution if you have to implement one of the other callbacks. We may run into this same limitation if we ever want to support batching generic actions too, though.