Fix openid_identifier XSS Vulnerability

This patch fixes a reflective XSS vulnerability that was assigned CVE-2013-1760 (related to Issue #1900). Although a fix was proposed for the latest release version, I found that the issue still exists. When login in, it is possible to insert the 'openid_identifier' parameter with JavaScript, causing an ErrorException that executes the code. For reference: www.thebuggenie.com/security/TBGSN-002-1