Organizational accounts

[peterthomassen]

Allow users to belong to organizations, authorized representatives of which can act in their name (= inspect/manipulate their domains).

[peterthomassen]

Design plan: #885, #886, #887, #888

This is closer to token sharing than to hierarchical accounts, so it works in "both directions" if needed. It also comes with scoping capabilities that may be pretty granular if needed.

[AlperShal]

Yes, this is really a necessity for a DNS hosting. Lots of times there are more than one people managing a domain's DNS entries and settings. It would be nice to not being forced to use one account.