[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!
@mmontenegro, do you really want a `for` loop for this? When `results` can be paginated, it is only ever an array with length = 1. I would consider re-writing these statements to eliminate the unnecessary loop.