Recently the server where I have installed several CMSs is offering free encryption certificate.
I have installed the certificate and I've done a 301 and displaying the page with Firefox I get a warning that all items are not secure.
Wordpress with "HTTPS WordPress" plugin and a 301 redirect is perfect.
My suggestion is a module to force the site http or https.
Previo view, here is my site: www.luxarve.com