Change how actors are retrieved from database

[rbruhn]

When retrieving actors (Zooniverse and GeoLocate) from the database with an Expedition, a collection is retrieved or haev to use a custom method to retrieve a particular actor: $expedition->zooniverseActor where zooniverseActor cannot be loaded lazily.

Create methods in the model to make calling a single actor easier by using actor_exxpedition as Pivot mode class.

[rbruhn]

Fixed with latest master-refactor push