also internationalize sessions controller

app/controllers/sessions_controller.rb

@@ -17,15 +17,15 @@ class SessionsController < ApplicationController
       else
         redirect_to_url = root_url
       end
-      redirect_to redirect_to_url, :notice => "Logged in!"
+      redirect_to redirect_to_url, :notice => I18n.t('sessions.logged_in')
     else
-      flash.now.alert = "Invalid email or password"
+      flash.now.alert = I18n.t('sessions.login_invalid')
       render "new"
     end
   end
 
   def destroy
     session[:user_id] = nil
-    redirect_to login_url, :notice => "Logged out!"
+    redirect_to login_url, :notice => I18n.t('session.logged_out')
   end
 end

config/locales/de/de.sessions.yml

@@ -8,3 +8,7 @@ de:
       password: 'Passwort'
       login: 'Anmelden'
       forgot_password: 'Passwort vergessen?'
+    # used in controller
+    logged_in: 'Logged in!'
+    logged_out: 'Logged out!'
+    login_invalid: 'Invalid email or password'