Make possible to use a block in button_to helper if button text is hard
to fit into the name parameter, e.g.:

    <%= button_to [:make_happy, @user] do %>
      Make happy <strong><%= @user.name %></strong>
    <% end %>
    # => "<form method="post" action="/users/1/make_happy" class="button_to">
    #      <div>
    #        <button type="submit">
    #          Make happy <strong>Name</strong>
    #        </button>
    #      </div>
    #    </form>"