Tweak integration tests so they're more easily run against a live server...

While working on the loadtest stack,I tweaks the existing integration tests so they're more easily run against a live server.  @dannycoates I hope this doesn't step on anything you already had in progress, it's just a quick bit of hacking to give us a stack-sanity-checking tool.

Run it like this:

    PUBLIC_URL="http://idp.loadtest.lcip.org" node test/run/integration_tests.js

With the loadtest server running in auto-verified mode, this produces some nice successful tests for me (modulo the 500-server-error thing from Issue #170).