Bug 31955: Add page-section div to additional-fields.tt

Bug 31955: Add page-section div to additional-fields.tt

To test:
1. Apply patch
2. Look at Administration > Additional fields.
3. Each of the 4 tables should have a page-section div around it:

    Order baskets (aqbasket)
    Subscriptions (subscription)
    Account lines (credit) (accountlines:credit)
    Account lines (debit) (accountlines:debit)

Note: There are some indentation changes.

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>