Fix original issue #

Fixes kayleecodes1#4

index.js

@@ -255,9 +255,14 @@ CASAuthentication.prototype._login = function(req, res, next) {
 
     // Set up the query parameters.
     var query = {
-        service: this.service_url + url.parse(req.url).pathname,
-        renew: this.renew
+        service: this.service_url + url.parse(req.url).pathname
     };
+
+    // see: https://jasig.github.io/cas/development/protocol/CAS-Protocol-Specification.html#parameters
+    // unless option is `true` do not set it as setting it equals `true` on the CAS server
+    if (this.renew === true) {
+        query.renew = true;
+    }
 
     // Redirect to the CAS login.
     res.redirect( this.cas_url + url.format({