Middlerawre that "translates" ids in results to strings

Conversion added to gender, period and ethnic group

Also included RQF. And /spatial/sociodemographic is usins RQF to build queries

Now you can join tables with composite foreign/primary keys using RQF. In the
join attribute just use an array of columns that need to be used in the join

* Create routes /enrollment/gender and /enrollment/ethnic_group
* Add gender and ethnic_group to enrollment params in RQF

Route /api/v1/simulation/time exists and works with parameter max_time

* Example route: `/api/v1/simulation/time?max_time=10`
* Return value: {"result": [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]}

If no value is specified in max_time, an error is returned