redirect http->https on racktables

racktables moved behind misc. varnish
recently, so SSL termination happens at nginx
and Apache doesn't speak it anymore

nevertheless we still want to redirect
http to https, so this is the identical way
we already do this in a bunch of other places
if you grep for it through the repo

Change-Id: Idc9a448f2a68b896fb0ebbe48401e09272095875