What a time to be alive! The internet is really winning. Need to setup HTTPS on your site check out letsencrypt.org. To get you started check out the getting started guide.
If you are hosted on Webfaction check out this client letsencrypt-webfaction. This should get you up and running in a very short time depending on how fast Webfaction support are. Painless I tell you.
Update Once setup on Webfaction you need to ensure all HTTP traffic is redirected to HTTPS to do this you can add the following snippet to your .htacess file.
For more info on redirecting to HTTPS see this answer on stackoverflow .
To get rid of the Webfaction site not configured error page, create a plain HTTP website that points to the desired application. In the end you will have both a HTTP and HTTPS version of the site. The HTTP version should then direct to the HTTPS site. Not too complicated right?