Use case-insensitive matching on email address

This patch addresses an issue where a client may have upper-case letters in
their email address. When visiting the client portal to check the ticket
status, previously, the exact same case would be required in the 'Email
Address' box.

This patch remove the case sensitivity for email logins.

include/class.ticket.php

@@ -176,7 +176,7 @@ class Ticket {
 
     function getAuthToken() {
         # XXX: Support variable email address (for CCs)
-        return md5($this->getId() . $this->getEmail() . SECRET_SALT);
+        return md5($this->getId() . strtolower($this->getEmail()) . SECRET_SALT);
     }
 
     function getName() {