Add difficulty levels

config/routes.rb

@@ -35,6 +35,8 @@ Osem::Application.routes.draw do
       post "/cfp" => "callforpapers#create", :as => "cfp_create"
       get "/event_types" => "eventtype#show", :as => "eventtype_list"
       put "/event_types" => "eventtype#update", :as => "eventtype_update"
+      put "/difficulty_levels" => "difficulty_levels#update"
+      resources :difficulty_levels
       resources :events do
         member do
           post :comment