Transparently re-route all CONNECT requests back to the gateway. This way,
browsers can route IPFS-enabled websites to the daemon by setting the gateway as
a "proxy". We'll then handle these websites the same way we handle normal
DNSLink websites.

This _also_ means the IPFS Companion can route ipfs.io traffic to the local
daemon _without_ touching the URL (well, we need to replace the https part with
http).

License: MIT
Signed-off-by: Steven Allen <steven@stebalien.com>