Ability to rename an organization (team site)

[fflorent]

After #903 has been implemented, a user has reported that he could not find how to rename the team site he created.

There is already a API endpoint that can be called, but that is a bit technical for users. Unless I am wrong, I think there is currently no other way.

That should be easy to be implemented regarding the development itself, still it would need some design work beforehand.

cc @lusebille