url_handlers: logout: Adjust the cookie expiry date format
url_handlers: logout: Adjust the cookie expiry date format

Change 01-Jan-1970 to 01 Jan 1970, this is the preferred format as
defined by RFC 1123.

Signed-off-by: Andrew Clayton <02e0a999c50b1f88df7a8f5a04e1b76b35ea6a88@opentechlabs.co.uk>

ac000/receiptomatic