Add to wrapper repositories a method to fetch all entities of their specific class which are children of a given location

[gggeek]

This seems to be quite a common scenario: ask to the specific Repository to load all children of location X filtering out all the ones which are of undesired type.
Apart from location Id, the API should include offset, limit and optional sort conditions.
Possibly, the developer should be able as well to add more filtering criteria to the query generated and used by the Repository.