Configurable refresh of user claims upon call to userinfo

[uberfirestone]

Some clients may require pulling an update from the definitive source of a user's claims before the userinfo object is returned.

This might be configurable at the provider level. (discussed 08/19/2015 in Gitter)

[christiansmith]

Added refresh_userinfo option with release 0.1.48. You can configure this property for the entire server or for a specific provider.

This is a step forward, doesn't quite solve the problem if I understand the requirements. I believe implementing #10 will bring us closer to getting it right. We've escalated that to a P1 and I'm closing this issue.