adding 404.html page for the page not found 404 error
adding style sheet for the 404.html page
updating urls.py => 404 error handler, adding the 404 view in views.py
	modified:   wui/views.py
make 404.html localizable
wui.views.custom_404 instead of app.views.custom_404
compress the 404.jpg image
/static/404/404.css insterad of ../wui/static/404/404.css