add user identity provisioning

@liggitt This builds on top of https://github.com/openshift/origin/pull/334, so I'll rebase it again once yours goes in, but I'm still looking for feedback.
User is fine.

----- Original Message -----
> > @@ -93,19 +99,25 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, req
> > *http.Request) {
> >  
> >  	glog.V(4).Infof("Got access data")
> >  
> > -	user, ok, err := h.provider.GetUserInfo(accessData)
> > +	userIdentityInfo, ok, err := h.provider.GetUserIdentity(accessData)
> 
> > info for UserInfo
> 
> I think info is too vague.  Can we agree on user?
> 
> ---
> Reply to this email directly or view it on GitHub:
> https://github.com/openshift/origin/pull/367/files#r20178204