Mirror the FindIterable and AggregateIterable APIs in the driver

[evanchooly]

Currently, Morphia has its own FindOptions and AggregationOptions for historical reasons. Given the recent changes to the APIs for querying and aggregation (namely, that they are themselves Iterable) it makes more sense to mirror how the driver sets those options via these two interfaces versus having overloads to take them. Transitioning to this style of API would simplify the API and reduce the surface area involved.