Support for PAPE: the OpenID Provider Authentication Policy Extension

This pull request provides the passport-openid module with support for the OpenID Provider Authentication Policy Extension (PAPE), as recently added to the node-openid module ( https://github.com/havard/node-openid/commit/5bb00828d46d67dce086fb1348efa56ffe8d03fd ).

The changes consist of some additional code in the strategy file, a new callback invoking section in "verifyAssertion", plus a new test case and a few changes to existing test cases.

Note: this will work with the github version of node-openid, but not the module on NPM, as this has not been updated yet.