Changeset 57b4525 for lib/oauth2.c

Nothing useful yet, this just generates an auth URL. Things to do: Ability
to process the answer. This is hard because the GTalk server will time out
very quickly which means we lose our state/scope/etc. (And the ability to
even receive the answer, at least if I'd do this the same way the Twitter
module does it.)

And then, get the access token and use it, of course. :-)