Task/395 pagination queries

### Description
Pagination implemented and with rudimentary unit tests.
URI params 'offset' and 'limit' used.
A third URI param 'details' steers whether 'mongo db count' command is issued on no hits.

This is to return the count to the caller? Mabye a (non cosnts) reference is more aligned with the function signatures that we are using now? E.g.:

```
..., (long long)& count)
```