Feature/redirect to https

There's no way of configuring the ELB to redirect; it just terminates HTTPS there and forwards everything to port 80. So I tweaked the ELB listener to forward 80 -> 80 and 443 -> 443 (but HTTP, not HTTPS). That way, nginx can reply to anything coming in on 80 with a 301. ( @dlapiduz, take note.)
(In theory, it's possible to get nginx doing this with a single server listener since ELB sends the origin port details through, but this requires use of `if` which has [all kinds of nasties](http://wiki.nginx.org/IfIsEvil).)

To make the site happy on HTTPS, a few asset references needed changing. Placeholder images have been downloaded for the moment because [placehold.it](http://placehold.it) doesn't do HTTPS.
I believe that using 443 in the clear is somewhat confusing. We can use any other port and make elb forward to it. What do you think about changing it to something else? 8080?

Like @konklone said, it might make sense to re encrypt the traffic and keep 443 but that would mean provisioning certs to the servers as well as the elb.