Support for migrating domains #18
Description
If a server admin decides to change the domain name where Quorra runs the client-derived keys will change, breaking existing registrations.
Keychains could offer a migration path - after the system administrator moves the Quorra server to a new domain, the user would enter the old domain and the new domain into a special migration flow dialog. The keychain would use both to create two signatures - for the old and new domain. After verifying, the server would replace the old public key with a new one.
The main obvious downside to this approach is that it requires user interaction, the good news is that the keychains can make this as easy as entering two addresses.