Add idp_auth_complete to the page_request_test.

issue #1794

tests/page-requests-test.js

@@ -63,6 +63,7 @@ suite.addBatch({
   'GET /privacy':                respondsWith(200),
   'GET /verify_email_address':   respondsWith(200),
   'GET /add_email_address':      respondsWith(200),
+  'GET /idp_auth_complete':      respondsWith(200),
   'GET /pk':                     respondsWith(200),
   'GET /.well-known/browserid':  respondsWith(200),
   'GET /signin':                 respondsWith(200),