Single sign out support

[dentarg]

See atmos/warden-github#46

We should probably use https://github.com/atmos/sinatra_auth_github which has support for that

[dentarg]

Related: if you sign in and after that update your membership (join/leave Starkast org on GitHub), we don't catch that

[dentarg]

sinatra_auth_github has been archived, so maybe not the best of options

warden-github has not been archived, maybe an option (need to build a little bit more ourselves)

https://github.com/atmos/warden-github#single-sign-out

[dentarg]

https://github.com/atmos/warden-github#single-sign-out

I don't this works for oauth apps you create yourself, sounds like it is only something GitHub can use:

OAuth applications owned by the GitHub organization are sent an extra browser parameter to ensure that the user remains logged in to github.com.

Yes, see: atmos/warden-github#51

[dentarg]

Maybe the new GitHub Apps can dome something like it, haven't checked.

[dentarg]

warden-github has not been archived

It is archived now 😢

[dentarg]

Possibly of interest: https://github.com/wardencommunity/sinatra_warden