persistent user accounts
All users created are currently lost when the application is recompiled.
The most general solution would be to make it possible to provide a custom SDS to store the user database. This would however require to make variants of all tasks in
iTasks.Extensions.Admin.UserAdmin parametrised with a SDS, which is quite some work.
For now it would be good enough to change the default behaviour to using a file
UserAccounts.json at a fixed path. Any objections, @baslijns?