Horde HTTPS redirect for login

From Julian Yap

Edit HTTP config:

# This allows for only having SSL login page.
RewriteEngine On
RewriteCond %{HTTPS} !=on
RewriteRule ^/horde/imp/login.php(.*) https://%{SERVER_NAME}/horde/imp/login.php$1 [R,L]

Edit main conf.php so that it uses 'HTTPS for login only' (option = 3).