Comments and contact person had feature flags created for their
visibility some time ago, but we missed a couple of sections in the
frontend. In addition, comments that were set on a role during
invitation was invisible later, defeating the purpose. They are now
visible if comments are enabled.

Resolves: GREG-197

Not all OUs have names in all languages in OrgReg. We now fallback to
english if norwegian names are missing and vice versa.

Resolves: GREG-178

Dates can now be changed after they have started and ended. This means
that there is no situation which needs disabling the input fields, and
disabling has been removed.

Start and end date can now be in the past. The following rules apply:
 - Start dates can be any date in the past, and no more into the future
   than the max days property of the role type.
 - End dates follow the same rules
 - End dates must be equal to or later than start date.

Notification publishing has been reviewed to ensure duplicate
notifications are not created when start or end date is today.

Resolve: GREG-148

Aria did not match label when changing langauge, and an id was
duplicated

- The hook returns the info for a single guest, and a function to reload
  that info from the api.
- The roles of the guest are now on the roles attribute of the guest
  object instead of as its own object.
- Adding a new role now triggers a reload of the data from the api after
  the post request has completed.

Resolves: GREG-114

An api path was missing a slash and a save button did not redirect back
to the previous location

Even though start_date can be optional in the payload, it will always be
present in the form.

Code for guest routes moved to their own folder so that we don't need
multiple api calls.
Serializer class for roles has been simplified with methods for
validation of each field and a separate one used in invites without
requiring the person field.

Resolves: GREG-61