OpenVPN connect fails if login contains special characters (e.g. &)
after upgrade pfSense to 2.2, OpenVPN fails connect for login S&V (authorization by AD).
openvpn: user 'S' could not authenticate.
Jan 28 20:37:42 openvpn: /openvpn.auth-user.php: ERROR! Either LDAP search failed, or multiple users were found.
Fixes #4340 encode username same as with password to avoid issues with special chars.