Ensure cookie path is set for the session cookie
Properly define ROOT_PATH
Fix regression detecting expired sessions
Use a non-standard session cookie name

Which will help against clobbering session cookies against other PHP
applications shared on a parent domain of the domain hosting osTicket or in
a parent folder or virtual folder.
Merge pull request #655 from greezybacon/issue/653

Ensure cookie path is set for the session cookie

Reviewed-By: Peter Rotich <peter@osticket.com>