Ensure that Flocker GitHub history remains accessible

[wallrj]

• Clarify whether the https://github.com/ClusterHQ/ organisation and the https://github.com/ClusterHQ/flocker repository (+issues, pull requests, wiki, pulse etc) will remain accessible.
• Maybe request that https://github.com/ClusterHQ/flocker be migrated to a new organisation under control of Flocker developers.
• Create a new GitHub organisation
• Choose 2 or 3 trusted users as organisation administrators.