config: add lsd group to STAFF_GROUPS

[MirruK]

Either add the lsd group to STAFF_GROUPS in production, or change the is_staff attribute to a field on every member. This way
date-admin or the board can go and manually set someone to have access to the admin panel, this is currently not possible.

[jaspnas]

We probably don't want to set this per-member, Maybe we should have a separate admin_access group that gives access to admin, and remove all other groups from STAFF_GROUPS

[MirruK]

Yes I like that suggestion, the staff_groups thing is not very flexible in all honesty