Serialization has been moved to serializer classes, sharing them when
sensible and Views have been converted to ViewSets to simplify code.

Separates the queryset and the serialization from each other.

The OU view deserves its own file, and the guest info is actually a
person view and should live with  the other person views.

The profile page of a guest now shows a verification button if the guest
has a passport or national identificaiton number that has not been
verified. Clicking the button shows a dialog, with a confirmation button
which triggers a PATCH request to the backend and reloads the page when
it returns.

Resolves: GREG-101

Does the same as before with less and more readable code.

Any user that does not have a GregUserProfile must be a superuser so
this is not a problem per se, but it should be handled. For now we
simply treat them as an anonymous user and deny access.

Resolves: GREG-116

Issue: GREG-121-FEIDE-EMAIL

Adding tests for a serializer prompted moving of view tests to their own
subdirectory.

Start dates can now be blank, check for correct sponsor has been moved
to the more appropriate validate method and we now check that the role
exists before doing anything in the serializer

If the user is neither a guest or a sponsor, generic text explaining
this is shown. If they are a guest, they are shown the data related to
them. If they are a sponsor, they are redirected to the /sponsor/ route.

Resolves: GREG-97

To prevent hammering on the invite endpoint we throttle requests to the
endpoint to 100/day per ip.

Resolves: GREG-84