Redirect to /contests after authentication

#25

app/controllers/concerns/authentication.rb

@@ -35,7 +35,7 @@ module Authentication
     end
 
     def after_authentication_url
-      session.delete(:return_to_after_authenticating) || root_url
+      session.delete(:return_to_after_authenticating) || "/contests"
     end
 
     def start_new_session_for(user)