BUG: required fields in subgroup creation form do not match new member form

[aguestuser]

[stub]

on subgroup creation form where we ask for organizer fields:

• we do not mark required fields with asterisks
• we do require phone number but do not require zip code (unlike the new member form where we require zip code but not phone number)

both are confusing. the latter is a logical error that contradicts the business needs expressed by clients.