title: Correctly assign HTTPS only custom domain to flex env
body: <p>What is the correct way to map a custom domain to Google App Engine project?</p>
  
  <p>I've added the custom domain, set up all the DNS records etc. and it is working! But how do I enforce HTTPS only? (Like the custom domain generated does)</p>
  
  <p>From reading around <em>many</em> posts I have seen <code>secure: always</code> in a <code>handler</code> which I have tried, but doesn't seem to work (saw some comments that it doesn't work on flex environments?)</p>
  
  <p>So how can I correctly map my domain to a flex php environment being HTTPS only?! Seems such a simple thing to want to be able to do!</p>