Set restraints on start year at user creation

Bart Hofman
2019-09-18T21:29:48+02:00

### One-sentence description

When creating a new user you can set the start year any number you want.

### Current behaviour / Reproducing the bug

As admin "create new user" and set as start year any number you wish

### Expected behaviour

Make a dropdown and be able to only select actually existing cohorts