pass team membership data to the underlying app in a "X-{whatever}" http header

[Stuart Metcalfe]

The openid is passed through to the underlying app with the "X-Remote-user" (iirc) header. We should do the same with the team membership data as a standard comma-separated string, same as is returned by sso/lp

[Stuart Metcalfe (stuartmetcalfe)]

Here a line which will work:

self.request.headers_in['X-OpenID-teams'] = teams_string # <- raw comma-separated string as returned by SSO

We just need to add this to the openidteams handler in a way which always adds this info to the request and overwrites anything the user may have passed in.