Add authanticate before checking role in referece-card form

Author: yzhoubk

app/controllers/reference_card_forms_controller.rb

@@ -84,6 +84,7 @@ def validate_recaptcha!
   end
 
   def require_admin!
+    authenticate!
     @user_is_admin = current_user.role?(Role.stackpass_admin)
     raise Error::ForbiddenError unless @user_is_admin
   end