rails エラーメッセージのタイトル日本語化

_error_messages.html.erb

<% if @user.errors.any? %>
<div id="error_explanation">
  <h2><%= t(:header, :model => t(:user, :scope => [:activerecord, :models]),
                     :count => @user.errors.count, :scope => [:activerecord, :errors, :template]) %></h2>
  <p><%= t(:body, :scope => [:activerecord, :errors, :template]) %></p>
  <ul>
    <% @user.errors.full_messages.each do |msg| %>
    <li><%= msg %></li>
    <% end %>
  </ul>
</div>
<% end %>