Allow direct access to tickets with email and num

Starting with osTicket 1.8.1, users must receive an email and follow a link
in the email to get access to the ticket. With this new option, the email
verification step can be avoided in osTicket 1.9, because access is now only
granted to exactly one ticket.
Merge pull request #999 from greezybacon/feature/quick-client-access

Allow direct access to tickets with email and num

Reviewed-By: Peter Rotich <peter@osticket.com>