Signing out of OAuth apps doesn't actually sign you out of Intercode

[nbudin]

Intercode doesn't implement single sign-out, so OAuth apps such as Cantrip and the Furniture app can't actually sign you out.

Doorkeeper documents how to do this here: https://github.com/doorkeeper-gem/doorkeeper/blob/c48fd2d989e761ab3ebe21698fcfa70261df7f57/lib/generators/doorkeeper/templates/initializer.rb#L429