Make validation requirements configurable

[bjrne]

A future user should be able to setup easily, which users have to be approved and what consequences this has (eg what fields are visible with an without validation)

[bjrne]

Github fail due to the "partly fixes 186"

[feeds]

But I am trying to think what else we need to cover here :D

[bjrne]

To me, it is not obvious, what implications this currently has apart from the validation process. For example, some fields will become publicly visible when disabling the validation process, right?

Rather than code changes, I feel like this could use more doc-strings, a paragraph in the rtdocs etc. :)