Provide support for the hybrid OpenID/OAuth extension

[James Henstridge]

This one is a bit of a wishlist: It would be nice if login.ubuntu.com supported the OpenID OAuth extension:

http://svn.openid.net/repos/specifications/oauth_hybrid/1.0/trunk/openid_oauth_extension.html

Currently if I want to develop a website that uses login.ubuntu.com OpenID accounts and wants to access the Ubuntu One API, I need to (a) authenticate the user via OpenID with https://login.ubuntu.com, and then (b) acquire an OAuth token for that user, which will involve the user authenticating via OpenID to https://one.ubuntu.com if I'm using U1's OAuth endpoints.

If login.ubuntu.com implemented this extension, I could have an authorised request token when (a) completes. The website could then exchange this request token for an access token (if login.ubuntu.com provided its own OAuth end points) without having to bounce the user off site a second time.