Group attendees into teams - manage teams module

Since almost all the hackathons have some kind of teaming, a module to manage teams is a welcome addition.

That and the ability to issue food vouchers/qrcodes :)
I guess that can be also done using the hardware module. Instead of having hardware, the user can have meals.

The issue names no files, tests, or entry points. Start by inspecting the existing module structure and the hardware module, then clarify whether team management, meal vouchers, and QR codes are in scope; completion criteria are not defined yet.

Written by the indexing model from the issue text.