Add link to features UI to manager dashboard

app/views/manager/application/_navigation.html.erb

@@ -23,4 +23,5 @@ as defined by the routes in the `admin/` namespace
   <hr />
 
   <%= link_to "Delayed Job", manager_delayed_job_path, class: "navigation__link" %>
+  <%= link_to "Features", manager_flipflop_path, class: "navigation__link" %>
 </nav>

config/routes.rb

@@ -15,6 +15,7 @@ Rails.application.routes.draw do
     post 'demandes/refuse_administrateur'
 
     authenticate :administration do
+      mount Flipflop::Engine => "/features"
       match "/delayed_job" => DelayedJobWeb, :anchor => false, :via => [:get, :post]
     end