RegistryNode: Team Support in User Management

[marcvanandel]

Besides Admins and Users (see #213 ) it might be required to have a more sophisticated rights system based on teams or departments within an Organization.

• Users should be added to at least one team or department (a.k.a. tag)
• Users could be added to multiple teams or departments (a.k.a. tag)
• a Device is managed by only one team / department (a.k.a. tag)
• Devices can only be edited / updated by someone who is part of the responsible team / department (a.k.a. has the same tag)
• when adding a new Device, the User needs to choose which team is responsible for it between the (optionally) multiple teams he is part of