i18n routing respects protocol

Previously, if a non-logged in user visited `https://www.reddit.com/i18n` they would be redirected to the *insecure* `http://www.reddit.com/r/i18n`

Site redirection should respect security settings.
From my basic testing, it looks like you can *use* relative urls, but it always ends up giving an `http://` address.  Dunno if this has to do with ssl-decryption/proxying.

@edent , could you add a comment with the explanation Ricky noted?