Force SSL on heroku

* This was previously done with NGINX configuration files.

config/environments/production.rb

@@ -52,7 +52,7 @@
   # config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect' # for NGINX
 
   # Force all access to the app over SSL, use Strict-Transport-Security, and use secure cookies.
-  # config.force_ssl = true
+  config.force_ssl = true
 
   # Use the lowest log level to ensure availability of diagnostic information
   # when problems arise.