Registrar: bulk admin change

[vohmar]

Registrar requested a feature to change admin contacts on multiple domains

This can only be done if ident data of old and new contact is identical otherwise this is considered as contact change and requires authorization from every registrant involved.

• Identically to bulk tech chance replace existing contact_id with another
• Admin contact tab should be added to the bulk change section (/registrar/bulk_change/new)
• Contact objects are replaced only if ident data of old and new object match (ident, ident type and ident country code)

[vohmar]

Please add a message to the bulk admin change view in registrar: "Bulk admin change is only allowed incase old and new contact share identical ident data ie for updating contact information."