Insert Letsencrypt::Middleware dynamically

Since all we have to do is check for force_ssl I don't see why we can't
just do that inside an initialize hook and change the way the middleware
is inserted accordingly.

Maybe I'm missing something obvious. This would reduce the amount of manual
configuration required for this gem.

Author: olivierlacan

lib/letsencrypt-rails-heroku/railtie.rb

@@ -3,6 +3,14 @@ class LetsencryptRailsHerokuRailtie < Rails::Railtie
     Letsencrypt.configure
   end
 
+  initializer "letsencrypt_rails_heroku.configure_rails_initialization" do |app|
+    if app.config.force_ssl
+      app.middleware.insert_before ActionDispatch::SSL, Letsencrypt::Middleware
+    else
+      app.middleware.use Letsencrypt::Middleware
+    end
+  end
+
   rake_tasks do
     load 'tasks/letsencrypt.rake'
   end