[MIE-1608] Added a simple pagination service and implemented it in every endpoint returning lists. 

Pagination Service receives a query object, like: {'offset': 1, 'limit': 50} and a list of items, and return a subset of that list representing the requested page. Default is set to  {'offset': 1, 'limit': 50}

Implemented Pagination Service in every endpoint returning lists. Example: if you go to */api/v1/object/db_user/1/activities* , you can add the query **?limit=20&offset=1** to the URL to filter your results.

Unit tests and bateries provided!
Instead of returning a singleton object, since the `Pagination` service only has one function, I think it would be cleaner to return the method directly. That would change the interface from `Pagination.paginate(req.query, items)` to `Pagination(req.query, items)`.