Before, closed disallowed guest edits completely, by removing
the `freely` permission. This makes it possible to explicitely bring
back guest-editing, but not guest-note-creation, to closed instances.
Signed-off-by: Dario Ernst <dario@kanojo.de>
This determines which ldap field is used as the username on
HackMD. By default, the "id" is used as username, too. The id
is taken from the fields `uidNumber`, `uid` or
`sAMAccountName`. To give the user more flexibility, they can
now choose the field used for the username instead.
